Q20
The rightmost non-zero digit of the number 302720 is
A.
1
AnswerB.
3
C.
7
D.
9
Answer: Option A
Solution
Answer: Option A
Solution:
(30)2720, we can write it as[(30)4]680Or,[(10 × 3)4]680
The right most non-zero digit depends on the unit digit of [(3)4]680
Unit digit of [(3)4]680,
Or, (81)680
The unit digit of 81 is 1 so any power of 81 will always give its unit digit as 1
Thus, required unit digit is 1