Published by:
CGP EDU Academic Team
Published on: August 12, 2026
The last non-zero digit in 20 ! is …………
Text Solution
Verified by ExpertsThe correct answer is:
4
Ans. 4
Sol. Find exponent of prime numbers like
2, 3, 5, 7, 11, 13, 17, 19 in 20 !
We get
20! = 2 18 . 3 8 . 5 4 . 7 2 . 11 1 . 13 1 . 17 1 . 19 1
= 10 4 (2 14 . 3 8 . 7 2 . 11 1 . 13 1 . 17 1 . 19 1 )
∴ 2 14 ends with 4, 7 2 ends with 9, 3 8 ends with 1 and product of remaining terms ends with 9. Hence least non-zero digit in 20! = 4
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