Assume a is not divisible by 10. (otherwise the problem is trivial).
<span>Define R(m) to be the remainder of a^m when divided by 10. </span>
<span>R can take on one of 9 possible values, namely, 1,2,...,9. </span>
<span>Now, consider R(1),R(2),......R(10). At least 2 of them must have the sames value (by the Pigeonhole Principle), say R(i) = R(j) ( j>i ) </span>
<span>Then, a^j - a^i is divisible by 10.</span>
Answer:
40
Step-by-step explanation:
why? because 40x40=1600
Answer:
1, 2, 3, 7, 10
Step-by-step explanation:
Step-by-step explanation:
here is your answer
enjoy
thanks to another users to give this answer
I got this picture from photomath, hope it helps
