What is the units' digit of 9^5 * 13^3 * 7^3 ?
[spoiler]OA 9. I don't like kaplan approach. Appreciate any help.[/spoiler]
[spoiler]OA 9. I don't like kaplan approach. Appreciate any help.[/spoiler]
Don't like Kaplan approach! Blasphemy!heshamelaziry wrote:What is the units' digit of 9^5 * 13^3 * 7^3 ?
[spoiler]OA 9. I don't like kaplan approach. Appreciate any help.[/spoiler]
I haven't looked at the official explanation (hard to believe, but I haven't memorized every Kaplan question), but we can solve fairly quickly by focusing on patterns of units digits.
9^1 = 9
9^2 = 81
9^3 = ..9
9^4 = ..1
9^5 = ..9
13^1 = ...3
13^2 = ... 9
13^3 = ...7
7^1 = 7
7^2 = ...9
7^3 = ...3
So, we have (...9)(...7)(...3) = (...3)(...3) = ...9
