Question on units digit

[neidelyncpina]

For the problem attached, you found the pattern of 2-4-3-1 and then came to the answer that when it’s 7^77, the remainder is 1.

I solved it by looking at the units digit patterns for 7 (7931) and then realized 7^77 will have a 7 units digit. So when 7/5 remainder = 2.

Is this also a correct way of solving or did I just get lucky?

Blockquote

[KevinM]

Hey, so I think your logic is ultimately the same as greg’s. Greg’s pattern already incorporates dividing the value by 5 ((7^1)/5 = 7/5 = remainder 2, then repeat for 4,3,1). On the other hand, your strategy is just waiting until you calculate the unit’s digit of 7^77 before dividing by 5 to find the remainder.

[neidelyncpina]

yay thanks!