A trailing zero is any zero that appears at the end of a number after all non-zero digits.

Trailing zeros appear when a number is a multiple of 10, which happens when the number includes factors of 2 and 5.

Example:

• \( 100 = 2^2 \times 5^2 \) → 2 trailing zeros
• \( 2500 = 2^2 \times 5^4 \) → 2 trailing zeros
• \( 720 = 2^4 \times 3^2 \times 5 \) → 1 trailing zero

Each trailing zero in a number corresponds to one pair of the factors \( (2, 5) \).