Try to solve this problem mentally and in less than six steps.
(5^6) - 1 is divisible by:
A) 58
B) 59
C) 61
D) 62
E) 86
I find that solving math problems can be surprisingly satisfying. I'll put my solution in the comments, in case any readers want to try it for themselves first.
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The difference of two squares:
ReplyDelete5^6 - 1 = (5^3 - 1)(5^3 + 1)
Left hand factor = 124 = 62 * 2
Thus the answer is "D".
How long did this take you? I came to the same conclusion in about 2mins.
ReplyDeleteYeah, around a minute, I think.
ReplyDelete