Modulo operator (%) in Python

The modulo operator (%) in Python is used to find the remainder after dividing one number by another. It works with both integers and floating-point numbers and is commonly used in tasks like checking even or odd numbers, repeating patterns, and calculations based on cycles. For Example:

10 % 3 = 1

This means when 10 is divided by 3, the remainder left is 1.

Let’s see how the modulo operator works in a Python program.

a = 10 % 4
print(a)

2

Explanation: 10 % 4 calculates the remainder when 10 is divided by 4, Since 4 goes into 10 two times with 2 left over, the result is 2

Syntax

a % b

Here, a is divided by b, and the modulo operator returns the remainder left after the division.

Modulo Operator with Negative or Float Numbers

Python also supports modulo operations with floating-point and negative numbers. The result always follows Python’s rule: the remainder has the same sign as the divisor.

x = 15.0
y = -7.0
print(x % y)

-6.0

Explanation: 15.0 is divided by -7.0. The remainder is adjusted to match the sign of the divisor (-7.0)

Using Modulo to Find Remainders in a Range

The modulo operator is often used to check patterns, such as remainders of numbers in a sequence.

n = 5
k = 3

for i in range(1, n + 1):
    print(i, "%", k, "=", i % k)

1 % 3 = 1
2 % 3 = 2
3 % 3 = 0
4 % 3 = 1
5 % 3 = 2

Explanation:

• Each number from 1 to 5 is divided by 3
• % returns the remainder for each division
• When the remainder is 0, the number is exactly divisible

ZeroDivisionError with Modulo Operator

Just like division, the modulo operator cannot work if the divisor is zero. Doing so raises a ZeroDivisionError.

a = 14
b = 0
print(a % b)

 Output

ERROR!
Traceback (most recent call last):
File "<main.py>", line 3, in <module>
ZeroDivisionError: integer modulo by zero

Explanation:

• The right operand of % must not be 0
• Python raises an error to prevent invalid mathematical operations

Checking Even or Odd Numbers Using Modulo

One of the most common uses of the modulo operator is to check whether a number is even or odd. A number is even if it leaves a remainder of 0 when divided by 2.

n = 8

if n % 2 == 0:
    print("Even number")
else:
    print("Odd number")

Even number

Explanation:

• n % 2 checks the remainder when n is divided by 2
• If the remainder is 0, the number is even
• Otherwise, the number is odd