Answer to Question #273744 in Discrete Mathematics for Hana

Question

What is the units digit in the expansion of 2 to the power of 727 ?

8

4

2

6

Answer 1

units digit of a number is the rightmost digit of the number

use rule:

for x^y : if y leaves non zero remainder r, when divided by 4,then

units digit of x^y = l^r (l is units digit of x)

we have: $3\equiv727(mod\ 4)$

then:

units digit is $2^3=8$

reference:

https://www.justquant.com/numbertheory/units-digit-of-a-number-raised-to-power/