The unit's digit of 39 raised to the 100th power is 9.
Explanation:
- The unit digit of 39 is 9.
- So, divide the power 100 by 9.
⇒ 100/9 = 11 and (remainder = 1)
Now check the unit digits of multiples of 9.
= 9 ⇒ unit digit = 9
= 81 ⇒ unit digit = 1
= 729 ⇒ unit digit = 9
= 6561 ⇒ unit digit = 1
- The unit digit repeats as 9 for odd power and 1 for even power.
- The remainder of 100/9 is 1, which is a odd number.
- Therefore, the unit digit of
= 9