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Arithmetic Operators

Python provides the standard math operators we are familiar with, plus a few others that make common calculations much faster.

Basic Arithmetic​

Python behaves like a calculator. It follows the standard order of operations (PEMDAS).

a = 15
b = 7

print(a + b)  # Addition (22)
print(a - b)  # Subtraction (8)
print(a * b)  # Multiplication (105)
22
8
105

Unique Python Operators​

If we're coming from C, we'll find these very handy for quick math.

Floor Division Vs Standard Division​

In Python, standard division (/) always results in a float (e.g., 10 / 2 = 5.0).
Use floor division (//) when we care only about the whole number part and want to chop off the decimal.

print(15 / 7)   # 2.1428... (Standard)
print(15 // 7)  # 2 (Floor)
2.142857142857143
2

Exponentiation and Modulo​

  • Raising one number to the power of another (**) is built directly into the language, replacing the need for pow().
  • The modulo operator (%) gives us the remainder of a division.
print(5 ** 3)    # 125 (5 to the power of 3)
print(15 % 7)    # 1 (Remainder)
125
1

Shorthand Operators​

We can modify a variable's value in place using shorthand.

counter = 10
counter += 5     # Same as counter = counter + 5
counter -= 2     # Same as counter = counter - 2
print(counter)   # Result: 13
13

Worth Mentioning: Identity and Membership​

  • is / is not: Checks if two variables point to the same memory object (Identity).
  • in / not in: Checks if a value exists within a collection (Membership).
x = [1, 2, 3]
y = [1, 2, 3]

# Identity: Are they the same object?
print(x is y)      # False (they are separate lists)

# Membership: Is 1 inside the list?
print(1 in x)      # True

Output:

False
True