7^103 = 7*(50-1)51
So expanding binomially we get last term as -7 so remainder = -7 or 18
7^103 = 7*(50-1)51
So expanding binomially we get last term as -7 so remainder = -7 or 18
other way is using congruences
72≡ (-1)(mod25)
So
(72)51≡ (-1)(mod25)
7102≡ (-1)(mod25)
7103 ≡(-7)(mod25)
≡(18)(mod25)
So the remainder is 18
i had also got -7, the same way ashish got it...
but why did we add it to 25....???