Question 26893: For wat intergral values of n is the expression 1n + 2n + 3n + 4n divisible by 5?
*note n values are writen in superscript* Answer by 303795(602) (Show Source):
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Whenever n is divisible by 4 the last digit of the total ends in 4. This number can not be divided by 5.
All other values of n end in 0. This is therefore divisible by 5.
Note n must be positive.
n Total
1 10
2 30
3 100
4 354
5 1300
6 4890
7 18700
8 72354
9 282340
10 1108650
11 4373500
12 17312754
13 68711380
14 273234810
15 1088123500