diff --git a/pandas-stubs/core/series.pyi b/pandas-stubs/core/series.pyi
index 9cdbbf91..db9d4919 100644
--- a/pandas-stubs/core/series.pyi
+++ b/pandas-stubs/core/series.pyi
@@ -25,6 +25,7 @@ from typing import (
     Generic,
     Literal,
     NoReturn,
+    TypeVar,
     overload,
 )
 
@@ -174,6 +175,8 @@ from pandas._typing import (
     VoidDtypeArg,
     WriteBuffer,
     np_ndarray_anyint,
+    np_ndarray_complex,
+    np_ndarray_float,
     npt,
     num,
 )
@@ -183,6 +186,8 @@ from pandas.core.dtypes.dtypes import CategoricalDtype
 
 from pandas.plotting import PlotAccessor
 
+_T_COMPLEX = TypeVar("_T_COMPLEX", bound=complex)
+
 class _iLocIndexerSeries(_iLocIndexer, Generic[S1]):
     # get item
     @overload
@@ -1580,6 +1585,51 @@ class Series(IndexOpsMixin[S1], NDFrame):
     # just failed to generate these so I couldn't match
     # them up.
     @overload
+    def __add__(
+        self: Series[Never],
+        other: num | _str | timedelta | Timedelta | _ListLike | Series | np.timedelta64,
+    ) -> Series: ...
+    @overload
+    def __add__(self: Series[int], other: Series[Never]) -> Series: ...
+    @overload
+    def __add__(
+        self: Series[int], other: _T_COMPLEX | Sequence[_T_COMPLEX] | Series[_T_COMPLEX]
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def __add__(self: Series[int], other: np_ndarray_anyint) -> Series[int]: ...
+    @overload
+    def __add__(self: Series[int], other: np_ndarray_float) -> Series[float]: ...
+    @overload
+    def __add__(self: Series[int], other: np_ndarray_complex) -> Series[complex]: ...
+    @overload
+    def __add__(self: Series[float], other: Series[Never]) -> Series: ...
+    @overload
+    def __add__(
+        self: Series[float],
+        other: int | Sequence[int] | np_ndarray_anyint | np_ndarray_float | Series[int],
+    ) -> Series[float]: ...
+    @overload
+    def __add__(
+        self: Series[float],
+        other: _T_COMPLEX | Sequence[_T_COMPLEX] | Series[_T_COMPLEX],
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def __add__(self: Series[float], other: np_ndarray_complex) -> Series[complex]: ...
+    @overload
+    def __add__(self: Series[complex], other: Series[Never]) -> Series: ...
+    @overload
+    def __add__(
+        self: Series[complex],
+        other: (
+            _T_COMPLEX
+            | Sequence[_T_COMPLEX]
+            | Series[_T_COMPLEX]
+            | np_ndarray_anyint
+            | np_ndarray_float
+            | np_ndarray_complex
+        ),
+    ) -> Series[complex]: ...
+    @overload
     def __add__(self, other: S1 | Self) -> Self: ...
     @overload
     def __add__(
@@ -1626,6 +1676,24 @@ class Series(IndexOpsMixin[S1], NDFrame):
     @overload
     def __or__(self, other: int | np_ndarray_anyint | Series[int]) -> Series[int]: ...
     @overload
+    def __radd__(
+        self: Series[Never], other: num | _str | _ListLike | Series
+    ) -> Series: ...
+    @overload
+    def __radd__(
+        self: Series[int], other: _T_COMPLEX | Sequence[_T_COMPLEX]
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def __radd__(self: Series[float], other: int | Sequence[int]) -> Series[float]: ...
+    @overload
+    def __radd__(
+        self: Series[float], other: _T_COMPLEX | Sequence[_T_COMPLEX]
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def __radd__(
+        self: Series[complex], other: _T_COMPLEX | Sequence[_T_COMPLEX]
+    ) -> Series[complex]: ...
+    @overload
     def __radd__(self, other: S1 | Series[S1]) -> Self: ...
     @overload
     def __radd__(self, other: num | _str | _ListLike | Series) -> Series: ...
@@ -1703,6 +1771,92 @@ class Series(IndexOpsMixin[S1], NDFrame):
     @property
     def loc(self) -> _LocIndexerSeries[S1]: ...
     # Methods
+    @overload
+    def add(
+        self: Series[Never],
+        other: (
+            Sequence
+            | np_ndarray_anyint
+            | np_ndarray_float
+            | np_ndarray_complex
+            | Series
+            | Scalar
+        ),
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series: ...
+    @overload
+    def add(
+        self: Series[int],
+        other: _T_COMPLEX | Sequence[_T_COMPLEX] | Series[_T_COMPLEX],
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def add(
+        self: Series[int],
+        other: np_ndarray_anyint,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[int]: ...
+    @overload
+    def add(
+        self: Series[int],
+        other: np_ndarray_float,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[float]: ...
+    @overload
+    def add(
+        self: Series[int],
+        other: np_ndarray_complex,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[complex]: ...
+    @overload
+    def add(
+        self: Series[float],
+        other: int | Sequence[int] | np_ndarray_anyint | np_ndarray_float | Series[int],
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[float]: ...
+    @overload
+    def add(
+        self: Series[float],
+        other: _T_COMPLEX | Sequence[_T_COMPLEX] | Series[_T_COMPLEX],
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def add(
+        self: Series[float],
+        other: np_ndarray_complex,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[complex]: ...
+    @overload
+    def add(
+        self: Series[complex],
+        other: (
+            Sequence[_T_COMPLEX]
+            | np_ndarray_anyint
+            | np_ndarray_float
+            | np_ndarray_complex
+            | Series[_T_COMPLEX]
+        ),
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[complex]: ...
+    @overload
     def add(
         self,
         other: Series[S1] | Scalar,
@@ -1945,6 +2099,92 @@ class Series(IndexOpsMixin[S1], NDFrame):
         min_count: int = ...,
         **kwargs: Any,
     ) -> Scalar: ...
+    @overload
+    def radd(
+        self: Series[Never],
+        other: (
+            Sequence
+            | np_ndarray_anyint
+            | np_ndarray_float
+            | np_ndarray_complex
+            | Series
+            | Scalar
+        ),
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: AxisIndex = ...,
+    ) -> Series: ...
+    @overload
+    def radd(
+        self: Series[int],
+        other: _T_COMPLEX | Sequence[_T_COMPLEX] | Series[_T_COMPLEX],
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def radd(
+        self: Series[int],
+        other: np_ndarray_anyint,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[int]: ...
+    @overload
+    def radd(
+        self: Series[int],
+        other: np_ndarray_float,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[float]: ...
+    @overload
+    def radd(
+        self: Series[int],
+        other: np_ndarray_complex,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[complex]: ...
+    @overload
+    def radd(
+        self: Series[float],
+        other: int | Sequence[int] | np_ndarray_anyint | np_ndarray_float | Series[int],
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[float]: ...
+    @overload
+    def radd(
+        self: Series[float],
+        other: _T_COMPLEX | Sequence[_T_COMPLEX] | Series[_T_COMPLEX],
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[_T_COMPLEX]: ...
+    @overload
+    def radd(
+        self: Series[float],
+        other: np_ndarray_complex,
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[complex]: ...
+    @overload
+    def radd(
+        self: Series[complex],
+        other: (
+            Sequence[_T_COMPLEX]
+            | np_ndarray_anyint
+            | np_ndarray_float
+            | np_ndarray_complex
+            | Series[_T_COMPLEX]
+        ),
+        level: Level | None = ...,
+        fill_value: float | None = ...,
+        axis: int = ...,
+    ) -> Series[complex]: ...
+    @overload
     def radd(
         self,
         other: Series[S1] | Scalar,
diff --git a/pyproject.toml b/pyproject.toml
index 29239c33..411a8364 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,11 +35,11 @@ types-pytz = ">= 2022.1.1"
 numpy = ">= 1.23.5"
 
 [tool.poetry.group.dev.dependencies]
-mypy = "1.16.0"
+mypy = ">=1.17.0"
 pandas = "2.3.0"
 pyarrow = ">=10.0.1"
 pytest = ">=7.1.2"
-pyright = ">=1.1.400"
+pyright = ">=1.1.403"
 ty = "^0.0.1a8"
 pyrefly = "^0.21.0"
 poethepoet = ">=0.16.5"
diff --git a/tests/__init__.py b/tests/__init__.py
index e0682a2d..c4a94e77 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -64,7 +64,7 @@ def check(
     if not isinstance(actual, klass):
         raise RuntimeError(f"Expected type '{klass}' but got '{type(actual)}'")
     if dtype is None:
-        return actual  # type: ignore[return-value]
+        return actual
 
     if isinstance(actual, pd.Series):
         value = actual.iloc[index_to_check_for_type]
@@ -82,7 +82,7 @@ def check(
 
     if not isinstance(value, dtype):
         raise RuntimeError(f"Expected type '{dtype}' but got '{type(value)}'")
-    return actual  # type: ignore[return-value]
+    return actual
 
 
 def pytest_warns_bounded(
diff --git a/tests/series/__init__.py b/tests/series/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/series/arithmetic/__init__.py b/tests/series/arithmetic/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/series/arithmetic/complex/__init__.py b/tests/series/arithmetic/complex/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/series/arithmetic/complex/test_add.py b/tests/series/arithmetic/complex/test_add.py
new file mode 100644
index 00000000..3b0f910b
--- /dev/null
+++ b/tests/series/arithmetic/complex/test_add.py
@@ -0,0 +1,95 @@
+import numpy as np
+import pandas as pd
+from typing_extensions import assert_type
+
+from tests import check
+
+left = pd.Series([1j, 2j, 3j])  # left operand
+
+
+def test_add_py_scalar() -> None:
+    """Test pd.Series[complex] + Python native scalars"""
+    i, f, c = 1, 1.0, 1j
+
+    check(assert_type(left + i, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + f, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(f + left, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_py_sequence() -> None:
+    """Test pd.Series[complex] + Python native sequence"""
+    i, f, c = [2, 3, 5], [1.0, 2.0, 3.0], [1j, 1j, 4j]
+
+    check(assert_type(left + i, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + f, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(f + left, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_numpy_array() -> None:
+    """Test pd.Series[complex] + numpy array"""
+    i = np.array([2, 3, 5], np.int64)
+    f = np.array([1.0, 2.0, 3.0], np.float64)
+    c = np.array([1.1j, 2.2j, 4.1j], np.complex128)
+
+    check(assert_type(left + i, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + f, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    # check(assert_type(i + l, "pd.Series[complex]"), pd.Series, np.complex128)
+    # check(assert_type(f + l, "pd.Series[complex]"), pd.Series, np.complex128)
+    # check(assert_type(c + l, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_pd_series() -> None:
+    """Test pd.Series[complex] + pandas series"""
+    i = pd.Series([2, 3, 5])
+    f = pd.Series([1.0, 2.0, 3.0])
+    c = pd.Series([1.1j, 2.2j, 4.1j])
+
+    check(assert_type(left + i, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + f, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(f + left, "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(f), "pd.Series[complex]"), pd.Series, np.complex128)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
diff --git a/tests/series/arithmetic/float/__init__.py b/tests/series/arithmetic/float/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/series/arithmetic/float/test_add.py b/tests/series/arithmetic/float/test_add.py
new file mode 100644
index 00000000..4ecdd744
--- /dev/null
+++ b/tests/series/arithmetic/float/test_add.py
@@ -0,0 +1,95 @@
+import numpy as np
+import pandas as pd
+from typing_extensions import assert_type
+
+from tests import check
+
+left = pd.Series([1.0, 2.0, 3.0])  # left operand
+
+
+def test_add_py_scalar() -> None:
+    """Test pd.Series[float] + Python native scalars"""
+    i, f, c = 1, 1.0, 1j
+
+    check(assert_type(left + i, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(f + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_py_sequence() -> None:
+    """Test pd.Series[float] + Python native sequence"""
+    i, f, c = [2, 3, 5], [1.0, 2.0, 3.0], [1j, 1j, 4j]
+
+    check(assert_type(left + i, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(f + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_numpy_array() -> None:
+    """Test pd.Series[float] + numpy array"""
+    i = np.array([2, 3, 5], np.int64)
+    f = np.array([1.0, 2.0, 3.0], np.float64)
+    c = np.array([1.1j, 2.2j, 4.1j], np.complex128)
+
+    check(assert_type(left + i, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    # check(assert_type(i + l, "pd.Series[float]"), pd.Series, np.float64)
+    # check(assert_type(f + l, "pd.Series[float]"), pd.Series, np.float64)
+    # check(assert_type(c + l, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_pd_series() -> None:
+    """Test pd.Series[float] + pandas series"""
+    i = pd.Series([2, 3, 5])
+    f = pd.Series([1.0, 2.0, 3.0])
+    c = pd.Series([1.1j, 2.2j, 4.1j])
+
+    check(assert_type(left + i, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(f + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
diff --git a/tests/series/arithmetic/int/__init__.py b/tests/series/arithmetic/int/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/series/arithmetic/int/test_add.py b/tests/series/arithmetic/int/test_add.py
new file mode 100644
index 00000000..bb4aec79
--- /dev/null
+++ b/tests/series/arithmetic/int/test_add.py
@@ -0,0 +1,95 @@
+import numpy as np
+import pandas as pd
+from typing_extensions import assert_type
+
+from tests import check
+
+left = pd.Series([1, 2, 3])  # left operand
+
+
+def test_add_py_scalar() -> None:
+    """Test pd.Series[int] + Python native scalars"""
+    i, f, c = 1, 1.0, 1j
+
+    check(assert_type(left + i, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(f + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_py_sequence() -> None:
+    """Test pd.Series[int] + Python native sequence"""
+    i, f, c = [2, 3, 5], [1.0, 2.0, 3.0], [1j, 1j, 4j]
+
+    check(assert_type(left + i, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(f + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_numpy_array() -> None:
+    """Test pd.Series[int] + numpy array"""
+    i = np.array([2, 3, 5], np.int64)
+    f = np.array([1.0, 2.0, 3.0], np.float64)
+    c = np.array([1.1j, 2.2j, 4.1j], np.complex128)
+
+    check(assert_type(left + i, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    # check(assert_type(i + l, "pd.Series[int]"), pd.Series, np.int64)
+    # check(assert_type(f + l, "pd.Series[float]"), pd.Series, np.float64)
+    # check(assert_type(c + l, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+
+def test_add_pd_series() -> None:
+    """Test pd.Series[int] + pandas series"""
+    i = pd.Series([2, 3, 5])
+    f = pd.Series([1.0, 2.0, 3.0])
+    c = pd.Series([1.1j, 2.2j, 4.1j])
+
+    check(assert_type(left + i, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left + f, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left + c, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(i + left, "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(f + left, "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(c + left, "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.add(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.add(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.add(c), "pd.Series[complex]"), pd.Series, np.complex128)
+
+    check(assert_type(left.radd(i), "pd.Series[int]"), pd.Series, np.int64)
+    check(assert_type(left.radd(f), "pd.Series[float]"), pd.Series, np.float64)
+    check(assert_type(left.radd(c), "pd.Series[complex]"), pd.Series, np.complex128)
diff --git a/tests/series/arithmetic/test_add.py b/tests/series/arithmetic/test_add.py
new file mode 100644
index 00000000..e1d054d2
--- /dev/null
+++ b/tests/series/arithmetic/test_add.py
@@ -0,0 +1,95 @@
+import numpy as np
+import pandas as pd
+from typing_extensions import assert_type
+
+from tests import check
+
+left = pd.DataFrame({"a": [1, 2, 3]})["a"]  # left operand
+
+
+def test_add_py_scalar() -> None:
+    """Test pd.Series[Any] + Python native scalars"""
+    i, f, c = 1, 1.0, 1j
+
+    check(assert_type(left + i, pd.Series), pd.Series)
+    check(assert_type(left + f, pd.Series), pd.Series)
+    check(assert_type(left + c, pd.Series), pd.Series)
+
+    check(assert_type(i + left, pd.Series), pd.Series)
+    check(assert_type(f + left, pd.Series), pd.Series)
+    check(assert_type(c + left, pd.Series), pd.Series)
+
+    check(assert_type(left.add(i), pd.Series), pd.Series)
+    check(assert_type(left.add(f), pd.Series), pd.Series)
+    check(assert_type(left.add(c), pd.Series), pd.Series)
+
+    check(assert_type(left.radd(i), pd.Series), pd.Series)
+    check(assert_type(left.radd(f), pd.Series), pd.Series)
+    check(assert_type(left.radd(c), pd.Series), pd.Series)
+
+
+def test_add_py_sequence() -> None:
+    """Test pd.Series[Any] + Python native sequence"""
+    i, f, c = [2, 3, 5], [1.0, 2.0, 3.0], [1j, 1j, 4j]
+
+    check(assert_type(left + i, pd.Series), pd.Series)
+    check(assert_type(left + f, pd.Series), pd.Series)
+    check(assert_type(left + c, pd.Series), pd.Series)
+
+    check(assert_type(i + left, pd.Series), pd.Series)
+    check(assert_type(f + left, pd.Series), pd.Series)
+    check(assert_type(c + left, pd.Series), pd.Series)
+
+    check(assert_type(left.add(i), pd.Series), pd.Series)
+    check(assert_type(left.add(f), pd.Series), pd.Series)
+    check(assert_type(left.add(c), pd.Series), pd.Series)
+
+    check(assert_type(left.radd(i), pd.Series), pd.Series)
+    check(assert_type(left.radd(f), pd.Series), pd.Series)
+    check(assert_type(left.radd(c), pd.Series), pd.Series)
+
+
+def test_add_numpy_array() -> None:
+    """Test pd.Series[Any] + numpy array"""
+    i = np.array([2, 3, 5], np.int64)
+    f = np.array([1.0, 2.0, 3.0], np.float64)
+    c = np.array([1.1j, 2.2j, 4.1j], np.complex64)
+
+    check(assert_type(left + i, pd.Series), pd.Series)
+    check(assert_type(left + f, pd.Series), pd.Series)
+    check(assert_type(left + c, pd.Series), pd.Series)
+
+    # check(assert_type(i + l, pd.Series), pd.Series)
+    # check(assert_type(f + l, pd.Series), pd.Series)
+    # check(assert_type(c + l, pd.Series), pd.Series)
+
+    check(assert_type(left.add(i), pd.Series), pd.Series)
+    check(assert_type(left.add(f), pd.Series), pd.Series)
+    check(assert_type(left.add(c), pd.Series), pd.Series)
+
+    check(assert_type(left.radd(i), pd.Series), pd.Series)
+    check(assert_type(left.radd(f), pd.Series), pd.Series)
+    check(assert_type(left.radd(c), pd.Series), pd.Series)
+
+
+def test_add_pd_series() -> None:
+    """Test pd.Series[Any] + pandas series"""
+    i = pd.Series([2, 3, 5])
+    f = pd.Series([1.0, 2.0, 3.0])
+    c = pd.Series([1.1j, 2.2j, 4.1j])
+
+    check(assert_type(left + i, pd.Series), pd.Series)
+    check(assert_type(left + f, pd.Series), pd.Series)
+    check(assert_type(left + c, pd.Series), pd.Series)
+
+    check(assert_type(i + left, pd.Series), pd.Series)
+    check(assert_type(f + left, pd.Series), pd.Series)
+    check(assert_type(c + left, pd.Series), pd.Series)
+
+    check(assert_type(left.add(i), pd.Series), pd.Series)
+    check(assert_type(left.add(f), pd.Series), pd.Series)
+    check(assert_type(left.add(c), pd.Series), pd.Series)
+
+    check(assert_type(left.radd(i), pd.Series), pd.Series)
+    check(assert_type(left.radd(f), pd.Series), pd.Series)
+    check(assert_type(left.radd(c), pd.Series), pd.Series)
diff --git a/tests/test_series.py b/tests/series/test_series.py
similarity index 100%
rename from tests/test_series.py
rename to tests/series/test_series.py