Q294
The unit digit in ( 122 )^173 is ?
The unit digit in is ?
A.
2
AnswerB.
4
C.
6
D.
8
Answer: Option A
Solution
Answer: Option A
Solution:
In this case:122 (powers of the last digit 2 )
21 = 2
22 = 4
23 = 8
24 = 16
25 = 32
26 = 64
27 = 128
28 = 256
29 = 512
……
As you can see, the pattern repeats every 4th power (2, 4, 8, 6).
We have to find 122173
Hence, remainder when 173 is divided by 4 = 1
(which corresponds to the 1st number of the pattern)
Thus, unit digit of 122173 = 2