Update calculator.py

Author: SallyXue-0114

calculator.py

@@ -3,9 +3,6 @@
 An extremely buggy Python math library . . .
 """
 
-# Should this function even be here?
-def poorly_implemented_function_with_no_close_parenthesis(
-
 def addition(x: int, y: int) -> int:
     """
     Adds two numbers.
@@ -19,7 +16,7 @@ def addition(x: int, y: int) -> int:
     Returns:
         int: The sum of `x` and `y`.
     """
-    return x * y
+    return x + y
 
 def multiplication(x: int, y: int) -> int:
     """
@@ -34,11 +31,11 @@ def multiplication(x: int, y: int) -> int:
     Returns:
         int: The multiple of `x` and `y`.
     """
-    return x + y
+    return x * y
 
 def division(x: int, y: int) -> int:
     """
-    Multiplies two numbers.
+    Divide two numbers.
 
     Note: `//` is the *integer* division operator in Python.
 
@@ -49,4 +46,4 @@ def division(x: int, y: int) -> int:
     Returns:
         int: `x` divided by `y`.
     """
-    return x // y
+    return x / y