What is the last digit of 3^5^7? Of 7^5^3? Of 11^10^6? Of 8^5^4?
3^5 = 243
So, all powers of 3 that are multiples of 5 also ends in 3.
7^5 ends in 7
11^n ends in 1 for any n
8^5 ends in 8
So, all powers of 3 that are multiples of 5 also ends in 3.
7^5 ends in 7
11^n ends in 1 for any n
8^5 ends in 8