What's the difference between / and // in Python?

/ always returns a float (10 / 4 = 2.5). // is integer division and discards the remainder (10 // 4 = 2). GCSE questions specifically test this distinction.

What does % mean in Python?

% is the modulo operator: it returns the remainder of a division. 10 % 3 is 1. It's most commonly used to test 'is this number even?' with n % 2 == 0.

Does Python follow BIDMAS?

Yes. Brackets first, then exponentiation, then multiplication/division, then addition/subtraction. Use brackets liberally to make intent clear.

Python arithmetic operators and expressions

GCSE Computer Science specifications all require pupils to use Python's arithmetic operators correctly and reason about the order in which they're evaluated. This unit covers +, -, *, /, integer division //, modulo %, exponentiation **, and how brackets change evaluation order (BIDMAS applies). It also introduces the classic exam distinction between / (returns a float) and // (returns an int, discarding the remainder) — the source of a large fraction of GCSE Python marks lost each summer. Perfect for classroom teaching, GCSE and A Level revision, and independent or home-schooled learners.

What you'll learn

Add, subtract, multiply and divide numbers
Distinguish / (float division) from // (integer division)
Use % (modulo) to test for even/odd and other remainders
Use ** for exponentiation (e.g. 2 ** 3 = 8)
Control evaluation order with brackets

UK GCSE topic coverage

Arithmetic operators (`+`, `-`)
Arithmetic operators (`*`, `/`)
Operators `//` and `%`
Operator `**`
Operator precedence (BIDMAS)
Dry-run and trace tables
Compound assignment (`+=`, `-=`, `*=`, `/=`)
Applied I/O and arithmetic

Worked example

Integer division and modulo

total_minutes = 137
hours = total_minutes // 60
minutes = total_minutes % 60
print(hours, "hours and", minutes, "minutes")

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Lessons in this unit

Full interactive lessons with checked tasks are available to signed-in RunPy users. Unit 1 and a selection of exam-style questions are free with a RunPy account.

Addition and subtraction with variables
Multiplication and division
Integer division and remainder
Powers and exponents
Order of operations
Tracing expressions with updates
Shortened update operators
Building multi-input programs

Frequently asked questions

What's the difference between / and // in Python?: / always returns a float (10 / 4 = 2.5). // is integer division and discards the remainder (10 // 4 = 2). GCSE questions specifically test this distinction.
What does % mean in Python?: % is the modulo operator: it returns the remainder of a division. 10 % 3 is 1. It's most commonly used to test 'is this number even?' with n % 2 == 0.
Does Python follow BIDMAS?: Yes. Brackets first, then exponentiation, then multiplication/division, then addition/subtraction. Use brackets liberally to make intent clear.