Numbers - General Aptitude

Q1:

What is the unit digit in (4137)754?

A 1

B 3

C 7

D 9

ANS:D - 9

Unit digit in (4137)754 = Unit digit in {[(4137)4]188 x (4137)2} =Unit digit in { 292915317923361 x 17114769 } = (1 x 9) = 9