Question: When 40! is expressed in base 8 form, what is the last non–zero digit in the base 8 expansion?

A) 2
B) 6
C) 4
D) 2 or 6

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Comments are closed.

  1. Pradeep kumar 3 years ago

    The last digit can be 4,2,8,6 if we multiple odd no to 4 so sir ,how can you say that it is always be 4

  2. very good question & even a better explanation sir

  3. Sir I solved a bit differently especially in the last part. Sir after getting that 12 zeroes part I surmised that the remaining digits would be a product of four and something odd. Typically (2k+1)*4. Hence 8k+4. Which leads also to the fact that it is in base 8 the 8k will be accommodated in the FIRST section of digits leaving the LAST 13 digits. Hence we are left with only 4 as the possible answer. Overall a very very challenging problem and one people should approach with a very calm and logical mind otherwise leave it entirely. Thank you Sir, for continuing to solve these for us!

  4. movies world 3 years ago

    Sir how we will solve this

    Find remainder when 8^100 is divided by 49

  5. shashank goyal 3 years ago

    Sir is it a cat level question?

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