CA Foundation · Quantitative Aptitude · Permutations and Combinations
The number of trailing zeros in 25! is:
25! has 6 trailing zeros. Each zero needs one factor 5 paired with a 2, and 5s are scarcer. Counting 5s gives 25/5 = 5 plus 25/25 = 1, total 6, because 25 contributes two factors of 5.
- A5
- B6Correct
- C7
- D4
Explanation
Trailing zeros come from factor pairs 2 × 5, and 5s are fewer than 2s. Count of 5s = floor(25/5) + floor(25/25) = 5 + 1 = 6. Option 5 misses the extra 5 contained in 25.
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