diff --git a/src/openfermion/ops/representations/polynomial_tensor.py b/src/openfermion/ops/representations/polynomial_tensor.py
index a2908d95a..26484ec6d 100644
--- a/src/openfermion/ops/representations/polynomial_tensor.py
+++ b/src/openfermion/ops/representations/polynomial_tensor.py
@@ -9,7 +9,7 @@
 #   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #   See the License for the specific language governing permissions and
 #   limitations under the License.
-"""Base class for representating operators that are polynomials in the
+"""Base class for representing operators that are polynomials in the
 fermionic ladder operators."""
 
 import copy
diff --git a/src/openfermion/ops/representations/quadratic_hamiltonian.py b/src/openfermion/ops/representations/quadratic_hamiltonian.py
index e08b2e55f..82fb56de5 100644
--- a/src/openfermion/ops/representations/quadratic_hamiltonian.py
+++ b/src/openfermion/ops/representations/quadratic_hamiltonian.py
@@ -130,7 +130,7 @@ def ground_energy(self):
         return numpy.sum(orbital_energies[numpy.where(orbital_energies < 0.0)[0]]) + constant
 
     def majorana_form(self):
-        r"""Return the Majorana represention of the Hamiltonian.
+        r"""Return the Majorana representation of the Hamiltonian.
 
         Any quadratic Hamiltonian can be written in the form
 
@@ -317,9 +317,9 @@ def index_map(i):
                 orbital_energies = numpy.concatenate((up_orbital_energies, down_orbital_energies))
                 diagonalizing_unitary_T = numpy.zeros((n_modes, n_modes), dtype=complex)
                 diagonalizing_unitary_T[: n_modes // 2, : n_modes // 2] = up_diagonalizing_unitary_T
-                diagonalizing_unitary_T[
-                    n_modes // 2 :, n_modes // 2 :
-                ] = down_diagonalizing_unitary_T
+                diagonalizing_unitary_T[n_modes // 2 :, n_modes // 2 :] = (
+                    down_diagonalizing_unitary_T
+                )
             else:
                 orbital_energies, diagonalizing_unitary_T = numpy.linalg.eigh(matrix)
 
diff --git a/src/openfermion/transforms/opconversions/qubitoperator_to_paulisum.py b/src/openfermion/transforms/opconversions/qubitoperator_to_paulisum.py
index 8fdf07c6b..0b58ce29d 100644
--- a/src/openfermion/transforms/opconversions/qubitoperator_to_paulisum.py
+++ b/src/openfermion/transforms/opconversions/qubitoperator_to_paulisum.py
@@ -48,7 +48,7 @@ def qubit_operator_to_pauli_sum(
         pauli_sum (PauliSum): cirq PauliSum object.
 
     Raises:
-        TypeError: if qubit_op is not a QubitOpertor.
+        TypeError: if qubit_op is not a QubitOperator.
     """
     if not isinstance(operator, QubitOperator):
         raise TypeError('Input must be a QubitOperator.')