Comparison Operators in Python

Every program you've written so far does the exact same thing every single time you run it — same input, same output, no thinking, no choice involved. But a real app needs to look at something, decide something, and react differently depending on what it found. That decision-making starts with comparison operators in Python and the boolean values they produce.

This page covers the modulus operator, every comparison operator, and how to combine conditions with and, or, and not — the building blocks for if statements.

What you will learn

• What the modulus operator % actually computes
• Every comparison operator: ==, !=, >, <, >=, <=
• The classic = vs == bug that trips up every beginner
• How to combine conditions with and, or, not
• Why Python treats non-zero numbers as truthy

The modulus operator: the remainder you forgot about

You already know how to divide numbers, but there are actually two results hiding inside every division problem. When you divide 7 by 3, the answer is 2 — but there is 1 left over that did not fit. That leftover piece is called the remainder. Python gives you the remainder using the % symbol, the modulus operator:

quotient  = 7 / 3    # 2.3333...   the result of dividing
remainder = 7 % 3    # 1            the leftover piece

Think of it like sharing sweets. If you have 7 sweets and 3 friends, each friend gets 2 sweets, and you have 1 sweet left over that does not divide evenly — that leftover 1 is exactly what 7 % 3 gives you.

The most common use of % is checking whether a number divides perfectly, with nothing left over. If x % y equals zero, then y divides evenly into x:

10 % 2    # 0   (10 divides evenly by 2, so it's even)
10 % 3    # 1   (10 does NOT divide evenly by 3)

You can also use it to pull out specific digits from a number, since the last digit of any number is just whatever is left after dividing by 10:

x = 12345
x % 10     # 5    just the last digit
x % 100    # 45   the last two digits

You will reach for % more often than you expect — especially when working with even/odd numbers, repeating patterns, or clocks.

Boolean expressions: questions with yes or no answers

Before a program can make a decision, it needs to be able to ask a question. In Python, every question has exactly two possible answers: True or False. An expression that gives you one of these two answers is called a boolean expression.

5 == 5    # True    (yes, 5 is equal to 5)
5 == 6    # False   (no, 5 is not equal to 6)

True and False are not words or strings — they are a special type of value in Python called bool. There are only two of them in the whole language, and every decision your program makes comes down to one of them.

Logical operators: combining conditions

Sometimes a single question is not enough — what if you need to check two things at once? Python gives you three tools for combining conditions, and they work almost exactly like the same words in English:

x > 0 and x < 10          # True only if BOTH are true (x is between 0 and 10)
n % 2 == 0 or n % 3 == 0   # True if AT LEAST ONE is true (n divides by 2 or by 3)
not (x > y)                # True if the thing after not is FALSE

• and requires both sides to be true. If either side is false, the whole thing is false.
• or only needs one side to be true. It is only false when both sides are false.
• not simply flips whatever comes after it — true becomes false, false becomes true.

For short-circuit evaluation, truth tables, and the difference between and/or versus the bitwise &/|, see the dedicated Logical Operators in Python page.

Truthiness: what counts as true or false beyond bool

Python is flexible about what counts as "true" or "false" outside of actual booleans. Any non-zero number is treated as true, and zero is treated as false:

17 and True    # True    (17 is non-zero, so it counts as true)
0 and True     # False   (0 is treated as false)

This flexibility can be useful later, but for now — until you are comfortable — stick to writing out your conditions explicitly with ==, !=, >, and so on. It keeps things clear.

Common mistakes

• Writing x = 5 when you meant to compare with x == 5
• Writing =< or => instead of <= and >=
• Forgetting that and needs both sides true, while or only needs one
• Assuming % gives you the division result instead of the remainder