Answer: 3^15
Step-by-step explanation:
Explained in attached picture. Hope you'll find it easy to understand. If not, you can comment :)
Multiply 250 by 120 and the answer is 300,000ft2
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>
It would b 9 x (-3^(x-1))