Answers

2016-05-04T05:05:12+05:30
Solutions 

30^2720 = 3^2720 * 10^2720

As 10^2720 produces all zeroes from right side, the last digit (unit digit) of 3^2720
is the right most non zero digit of 30^2720.

To find the unit digit of 3^2720:

( refer to “Magic of Numbers )

As 2720 is multiple of 4, we consider 4th digit of the unit digit pattern of 3n.
The unit digit pattern of 3n is 3,9,7,1


Answer is (1)  

≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

Another way to solve this is =

30^1=3 

30^2=9 

30^3=7 

30^4=1 

The pattern repeats from here. 

2720/4 gives the remainder 0 

Right most digit is 1.
0