MA wrote:

If x is a positive integer, what is the units digit of \((24)^{(2x + 1)}*(33)^{(x + 1)}*(17)^{(x + 2)}*(9)^{(2x)}\) ?

A. 4

B. 6

C. 7

D. 8

E. 9

The rightmost factor -- \(9^{2x}\) -- will have a units digit of 1 for any nonnegative value of \(x\).

Thus, the rightmost factor can be ignored.

All of the remaining exponents will be positive integers even if \(x=0\).

Thus, we can solve by letting \(x=0\) and raising the units digits of the first 3 factors to the resulting exponents:

\(4^1 * 3^1 * 7^2 = 12 * 49\) = integer with a units digit of 8.

_________________

GMAT and GRE Tutor

Over 1800 followers

Click here to learn more

GMATGuruNY@gmail.com

New York, NY

If you find one of my posts helpful, please take a moment to click on the "Kudos" icon.

Available for tutoring in NYC and long-distance.

For more information, please email me at GMATGuruNY@gmail.com.