Question
Let a number n have its base -7 representation as n= 1223334444. the highest power of 7, that divides the number n! is
Joshi sir comment
n = (1223334444)7 = 1*79 + 2*78 + 2*77 + 3*76 + 3*75 + 3*74 + 4*73 + 4*72 + 4*71 + 4*70
so if we will divide n! by 7x we will get 1*78 + 2*77 + 2*76 + 3*75 + 3*74 + 3*73 + 4*72 + 4*71 + 4*70 as x
A light example
if we divide (1*72 + 2*71 + 3*70)! by 7x we get x = 1*71 + 2*70 = 9
Read 1 Solution.
but this gives the answer to be (n-4)/7 but the answer is n/6-5
AMIT DAS 12 year ago
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