Question

What is the unit digit of 7to the power 105?

Answer 1

unit digit in 7¹°⁵ =  [ (7⁴)²⁶ x 7 ]

and, 

unit digit in (7⁴)²⁶ = 1

unit digit in 7¹°⁵ = (1 x 7) = 7

i hope it helps...........