Friday, August 21, 2009

GMAT Question of the day

Find the unit digit of the (3127)^173.

A)1
B)7
C)9
D)3


Unit digit in 3127 is 7
So if power is 1 then unit digit is 7
if power is 2 then unit digit is 9
if power is 3 then unit digit is 3
if power is 4 then unit digit is 1
and if power is 5 then unit digit is 7 and it will repeat
So dividing 173 by 4 remainder is 1
So at 1 unit digit will be 7
So 7 is answer