thank you in advance.
I do know that the four possibilities are 7, 9, 3, and 1. But after that, I'm stuck
I do know that the four possibilities are 7, 9, 3, and 1. But after that, I'm stuck
You know that 7^x repeats unit digits every fourth index.
7^1 = 7
7^2 = 9
7^3 = 3
7^4 = 1
7^5 = 7 (Again)
..
..
Now take the power 7777 and mod it by 4 (As it repeats every fourth index)
7777 % 4 = 1. Remainder is 1.
Raise the base 7 to the power 1 i.e. remainder. 7^1 = 7
So, units digit of 7^7777 = 7
Sorry, a typo.
