Even or Odd Program in Python

Problem statement

Read a number and print whether it is even or odd. Zero counts as even, and negative numbers follow the same rule as positives.

Approach 1: simple loop

Test the remainder of division by 2. A number that divides evenly by 2 leaves remainder 0 — that is the definition of even, and % gives you the remainder directly.

n = 7
if n % 2 == 0:
    print("Even")
else:
    print("Odd")
# Output: Odd

The condition reads like the maths: "if the remainder of n divided by 2 equals 0". Everything else is printing the answer.

Approach 2: reusable function

Wrap the test in a function that returns a boolean. The program then reads as a question and an answer, and the same function works for any list of numbers.

def is_even(n):
    return n % 2 == 0

print(is_even(10))   # True
print(is_even(7))    # False
print(is_even(0))    # True
print(is_even(-3))   # False

Returning True/False instead of printing inside the function keeps the decision reusable — the caller decides what to do with it.

Approach 3: Pythonic alternative

Python lets you pick a value with a conditional expression, which is handy when the output itself must be a word. The bitwise test n & 1 is the compact alternative — it checks the last binary digit.

for n in [4, 7, 0, -3]:
    print(n, "Even" if n % 2 == 0 else "Odd")
# Output:
# 4 Even
# 7 Odd
# 0 Even
# -3 Odd

Note that Python's % behaves politely with negatives: -3 % 2 is 1, so -3 is correctly reported as odd — no special case needed.

Dry run

For input 7: 7 % 2 means "7 divided by 2 leaves what remainder?" — 2 goes into 7 three times (6), remainder 1. Comparing 1 == 0 gives False, so the if branch is skipped and else runs, printing Odd. For 0: 0 % 2 is 0, the comparison is True, and Even prints. Trace every input the same way: remainder first, comparison second, branch third.

Common errors

Writing n % 2 = 0 — single = assigns; comparison needs ==.
Assuming negatives need a special case — in Python they do not: -3 % 2 is 1.
Using input() without int(): "7" % 2 raises a TypeError.
Testing n / 2 == 0 (division) instead of n % 2 == 0 (remainder).
Forgetting that 0 is even — the else branch would mislabel it.

Practice on PyDebug

Turn the idea into a debugging habit with these free browser exercises: