Quantitative Aptitude Ques 887
Question: The unit digit in the product $ {{(122)}^{173}} $ is
Options:
A) 2
B) 4
C) 6
D) 8
Show Answer
Answer:
Correct Answer: A
Solution:
- We know, $ 2^{1}=2 $
$ \Rightarrow $ $ 2^{2}=4 $
$ \Rightarrow $ $ 2^{3}=6 $
$ \Rightarrow $ $ 2^{4}=16 $
$ \Rightarrow $ $ 2^{5}=32 $
$ \Rightarrow $ 2 repeats at unit place after power of 4. Now, $ {{(122)}^{173}}={{(122^{4})}^{43}}\times 122 $ Unit digit in $ {{(122)}^{173}} $ = Unit digit in $ {{(122^{4})}^{43}}\times $ Unit digit in 122 = Unit’s digit in $ (6\times 2)=2 $
BETA
