Carcass wrote:
Which of the following could be the units digit \(98^x\), where x is an integer greater than 1?
Indicate
all such digits:
❑ zero
❑ 1
❑ 2
❑ 3
❑ 4
❑ 5
❑ 6
❑ 7
❑ 8
❑ 9
98^1 = 9
898^2 = (98)(98) = ---
4 [note: we need only recognize that the units digit of 98^2 will be equal to the units digit of (8)(8), which is 4]98^3 = (98)(98)(98) = (---4)(98) = ----
2 [note: we need only recognize that the units digit of (---4)(98) will be equal to the units digit of (4)(8), which is 2]98^4 = (98)(98)(98)(98) = (----2)(98) = ----
6 98^5 = (98)(98)(98)(98)(98) = (----6)(98) = ----
8 At this point, we are repeating the pattern. So, there's no need to continue.
The pattern of units digits will be
8,
4,
2,
6,
8,
4,
2,
6,
8, etc
Answer: 2, 4, 6, 8 (C, E, G, I)
Cheers,
Brent
_________________
Brent Hanneson – Creator of greenlighttestprep.com
Sign up for our free GRE Question of the Day emails
close
50% (00:51) correct
