Python Even Number Program

What Is an Even Number?

An even number is an integer divisible by 2 with remainder 0. In math form: n = 2 * k for some integer k.

n is even  ↔  n % 2 == 0

Examples:
  10 % 2 == 0  → even
  11 % 2 == 1  → odd
   0 % 2 == 0  → even
  -4 % 2 == 0  → even

How to Check an Even Number in Python

Four clear steps — then pick modulo, bitwise, or a step-by-two range loop.

1. Read the integer n (positive, negative, or zero).
2. Compute n % 2 (or check the least significant bit with n & 1).
3. If the remainder is 0 (or the LSB is 0), n is even.
4. To list evens in a range, test each value — or start at the first even and add 2.

Pseudocode

function IsEven(n):
    return (n mod 2) == 0

function PrintEvens(start, end):
    for i from start to end:
        if IsEven(i):
            output i

// Faster range listing:
function PrintEvensStep(start, end):
    i = start
    if i is odd:
        i = i + 1
    while i <= end:
        output i
        i = i + 2

Cheat Sheet

Keep these facts handy while writing the program.

Live Preview

Enter any integer to see the remainder and the even/odd verdict.

n = 10
n % 2 = 0
(n & 1) = 0
Verdict: EVEN

Worked Walkthrough — n = 10

Apply the modulo rule, then confirm with the bitwise check.

Step 1: Compute 10 % 2
        10 = 2 * 5 + 0
        remainder = 0

Step 2: Remainder is 0 → even

Step 3: Bitwise check
        10 in binary ends with 0
        (10 & 1) = 0 → same answer

Verdict: 10 is even

Python Programs

Start with the modulo helper — it is the clearest interview answer. Then reuse it for a range, and finish with the bitwise shortcut.

def is_even(n: int) -> bool:
    return n % 2 == 0


number = 10

if is_even(number):
    print(f"{number} is an even number.")
else:
    print(f"{number} is not an even number.")

10 is an even number.

def is_even(n: int) -> bool:
    return n % 2 == 0


start = 1
end = 10

print(f"Even numbers from {start} to {end}:")
for i in range(start, end + 1):
    if is_even(i):
        print(i, end=" ")
print()

Even numbers from 1 to 10:
2 4 6 8 10

def is_even_bitwise(n: int) -> bool:
    return (n & 1) == 0


samples = [10, 11, 0, -4]
for n in samples:
    label = "even" if is_even_bitwise(n) else "odd"
    print(f"{n}: {label}")

10: even
11: odd
0: even
-4: even

Time and Space Complexity

A single parity test is constant time. Range printers grow with how many integers you visit.

Key Takeaways