Remainder Hunt

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

What are the possible remainders when the $100^{th}$ power of an integer is divided by $125$? To reduce the number of cases to be checked, express the number as $5p+q $ where $p $ and $q $ are integers and $q=1,2,3,4 $ and find the hundredth power using the Binomial Theorem.

Published May 2002.