Latest CAT Aptitude Question SOLUTION: Last non-zero digit of a number 26!.

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(#M40013711) CAT question Keep an EYE

Last non-zero digit of a number 26!.

Asked In CAT Amit kumar (12 years ago)

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Aman  (12 years ago)

Last non-zero digit of a number 26!. will be 4.

Rightmost non-zero digit of n! or R(n!)


R(n!) = Last Digit of [ 2^a x R(a!) x R(b!) ]

where n = 5a + b
here n=26
a=5; b=1
R(n!) = Last Digit of [ 2^a x R(a!) x R(b!) ]
R(26!) = Last Digit of [ 2^5 x R(5!) x R(1!) ]= last digit of (2*2*1+ =4

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