Discussion

Explanation:

Here, factorials of number 5 and above are always divisible by 15, hence we can ignore them.

So the question simplifies to finding remainder of 1! + 2! + 3! + 4! when divided by 15.

= Remainder of (1 + 2 + 6 + 24) / 15

= Remainder of (33) / 15

= 3

Hence, 3.

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Doubts


ayushi said (2024-05-23 09:35:55)

if the number would have been 17 instead of 15 then how to solve

Reply from Admin:

Factorial of any number greater than 4 will always be divisible by 5.

Even if the number was 17, we would still consider one 1! + 2! + 3! + 4! for the remainder as 5!, 6!, ..., 17! will all give remainder 0 when divided by 5.

Hope this helps.


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