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Factorial Difference Digits (Posted on 2014-01-12) Difficulty: 3 of 5
Determine the last two non-zero digits of 36! - 24!

Extra Challenge: Solving this puzzle without a computer program.

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

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Solution re: How it could be done with a calculator (spoiler) | Comment 5 of 6 |
(In reply to How it could be done with a calculator (spoiler) by Charlie)

I have got the same 2 last digits by EXCEL column ,  starting with

a column of 23 numbers 2,3,...24 with 16 replaced by 1 and 5,10,15,20 by 1,2,3,4.
Going down with  p(n)=MOD(n*p(n-1),100) resulted with 36.

Answer: the last two digits are 6 and 4.

  Posted by Ady TZIDON on 2014-01-13 01:23:57
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