Hello, Ashsh!

IthinkI've solved it . . .

SinceFind the remainder of divided by 16

. . we have: .

Now consider consecutive powers-of-5 (mod 16):

. .

The remainders step through a 4-step cycle: .

Now we must determine: .

We have: .

Hence: .

And: . has remainder 13.

Therefore: .

But someone check my reasoning and work ...please!

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