What is the units digit of 9^19 - 7^15?
a) 2
b) 4
c) 5
d) 6
e) 7
Please assist with above problem.
a) 2
b) 4
c) 5
d) 6
e) 7
Please assist with above problem.
This can be solved by identifying the repeating digits for each exponential.
9^1 has 9 as the units digit.
9^2 has 1,and repeats. So the units digit of 9^19 has 9 as its units digit.
Similarly, 7^X has 7,9,3 and 1,repeating. So, 7^15 has 3 as its units digit.
9-3=6
