Numbers & Arithmetic

Perform calculations with integers and floats

Numbers & Arithmetic — Doing Math in Python

What Is It?

Python can do math — addition, subtraction, multiplication, division, and more. The math operators work much like a calculator, but with the power to use variables so your calculations adapt to changing data.

Syntax

python

a = 10
b = 3

print(a + b)   # Addition: 13
print(a - b)   # Subtraction: 7
print(a * b)   # Multiplication: 30
print(a / b)   # Division: 3.333...
print(a // b)  # Integer division: 3 (drops decimal)
print(a % b)   # Modulo (remainder): 1
print(a ** b)  # Exponent: 10³ = 1000

Operator	Name	What it does	Example	Result
`+`	Addition	Adds two numbers	`5 + 3`	`8`
`-`	Subtraction	Subtracts right from left	`10 - 4`	`6`
`*`	Multiplication	Multiplies	`6 * 7`	`42`
`/`	Division	Always returns a float	`10 / 3`	`3.333...`
`//`	Integer division	Drops the decimal	`10 // 3`	`3`
`%`	Modulo	Remainder after division	`10 % 3`	`1`
`**`	Exponent	Raises to power	`2 ** 3`	`8`

How It Works

Python follows the standard order of operations (PEMDAS: Parentheses, Exponents, Multiplication/Division, Addition/Subtraction):

python

result = (5 + 3) * 2 ** 2
# Step 1: Parentheses → (5 + 3) = 8
# Step 2: Exponent → 2 ** 2 = 4
# Step 3: Multiplication → 8 * 4 = 32
print(result)  # 32

Why Use Math in Code?

Almost every program does some form of math:

**E-commerce** — calculate totals, taxes, discounts: `total = price * quantity * (1 + tax_rate)`

**Games** — track score, health, damage: `health = health - damage`

**Data analysis** — averages, percentages, trends

**Physics simulations** — velocity, acceleration, distance

The modulo operator % is especially useful — it tells you if a number is even (number % 2 == 0) or helps cycle through options.

Common Mistakes

❌ Wrong	Why	✅ Right
`result = 10 / 3` expecting `3`	`/` always gives a float	Use `//` for integer: `10 // 3`
`price = 5 + 3 * 2` expecting `16`	Multiplication happens before addition!	Use parentheses: `(5 + 3) * 2`
`result = "5" + 3`	Can't add string + number — TypeError	Convert first: `int("5") + 3`
`print(2 ** 3 * 4)`	`*` has higher precedence than ``	Know your operator precedence

Your Turn!

Create two variables x = 15 and y = 4. Calculate and print:

The sum of x and y

x divided by y (regular division)

The remainder when x is divided by y

x raised to the power of y

💡Need a hint? (3 available)

#1Use print() to display each calculation

#2Remember the difference between / and //

#3The % operator gives the remainder

🔑Show solution (try it yourself first!)

x = 15
y = 4
print(x + y)
print(x / y)
print(x % y)
print(x ** y)

✏️ Code Editor

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📤 Output

Write your solution and click "Run Code" to test it!

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