Question

guys
Another one from WBJEE
i advise ALL not to post their solutions,i will give mine first then you all have the liberty of checking it and giving suggestions

Answer 1

the remainder obtained when
1!+2!+3!+ ....+ 95! is divided by 15....is????

Answer 2

since it says divisible by 15 i need to find the factor of 15 which is located here
5!+6!+7!+.....+95!,hence the terms before it cannot be divisble by it
hence remainder=(1!+2!+3!+4!)/15
=33/15
Remainder is 3,isnt it.....
@Ishaan94
@asnaseer
@Mani_Jha
@apoorvk

Answer 3

Looks good to me.

Answer 4

any suggestions????

Answer 5

Suggestions for what? It seems as if you've already solved the problem.

Answer 6

you are right

Answer 7

perfect logic i would say

Answer 8

no, i was asking for any other better methods of solving it,(shorter time saving methods)

Answer 9

every factorial from 5! to 95! is obviously divisible by 15

Answer 10

What you have is a very very short method.

Answer 11

Sarkar - your solution is correct. perfectly logical and simple.

Answer 12

oh is it???thanks.....

Answer 13

yw

Answer 14

Wow, I posted "EXACTLY!!" just the moment you put this question on, but it didn't show! I wonder why.


Yes, you solution is perfect, and that's exactly the way I had done it in the exam.