Basic Math Operations

Python as a calculator

Python can do math directly in your code. That means you can use it like a calculator, but with the extra power of variables, formulas, and program logic.

This module teaches the operators that appear in beginner Python again and again.

The four basic operations

The first operators are the ones you already know from school.

python
print(5 + 3)
print(10 - 4)
print(6 * 7)
print(8 / 2)

These mean:

• + addition
• - subtraction
• * multiplication
• / division

They work with variables too.

python
width = 8
height = 5
area = width * height
print(area)

Division gives a float

A detail that surprises many beginners is that / returns a float.

python
print(10 / 2)

The result is 5.0, not 5.

Python does this because regular division is treated as decimal division.

Floor division with //

If you want the whole-number result of a division, use //.

python
print(14 // 4)

This gives 3.

Floor division is useful when you want complete groups, positions, or counts without the decimal part.

The remainder with %

The % operator gives the remainder after division.

python
print(14 % 4)

This gives 2.

The modulo operator is very useful. A classic example is checking whether a number is even or odd.

python
print(8 % 2)
print(7 % 2)

If the remainder is 0, the number is even.

Powers with **

Python uses ** for powers.

python
print(2 ** 3)
print(5 ** 2)

These mean 2 to the power of 3 and 5 squared.

This operator appears often in beginner math formulas.

Square roots and powers

A square root can be written as a power of 0.5.

python
print(9 ** 0.5)

This gives 3.0.

You do not need advanced math here. The important idea is that Python can handle more than just simple addition and subtraction.

Using variables in math

Math becomes much more useful when the values come from variables.

python
price = 12
quantity = 4
total = price * quantity
print(total)

This makes formulas easier to read and easier to change.

Operator precedence

Python does not always calculate from left to right. It follows rules called operator precedence.

For example:

python
print(2 + 3 * 4)

The multiplication happens first, so the result is 14, not 20.

A simple rule is:

1. parentheses first
2. powers
3. multiplication and division
4. addition and subtraction

When parentheses help

Parentheses make your intention clear.

python
print((2 + 3) * 4)

Now the result is 20 because the addition happens first.

Even when Python would already do the correct thing, parentheses often make beginner code easier to understand.

Common math patterns in beginner code

These patterns appear again and again:

python
average = (10 + 20 + 30) / 3
seconds = minutes * 60
bmi = weight / (height ** 2)

Once you understand the operators, these formulas become much easier to read.

Common mistakes to avoid

A few mistakes happen often in this module:

• using / when you expected a whole number
• forgetting that % gives a remainder, not a percentage
• forgetting parentheses in a formula
• mixing text and numbers in the same calculation

When a result looks strange, check the operator you used and the order of the calculation.

What this lesson should give you

After this lesson, you should understand how to:

• add, subtract, multiply, and divide in Python
• use //, %, and **
• read and write simple formulas
• use variables inside math expressions
• understand the order in which Python evaluates expressions
• use parentheses to make formulas clear

These ideas will support many later exercises, including calculators, converters, and data-processing tasks.