What is the units' digit of 9^7 \times 17^3 \times 3^3 ?

GMAT Quantitative Reasoning Practice Test 4

Question : 13 of 100

Marks: +1, -0

What is the units' digit of

9^7 × 17^3 × 3^3

Solution:

17^3 × 3^3=(17 × 3)^3=51^3=51 × 51 × 51 →

the units' digit is just

1 × 1 × 1=1

.
We are left with the units' digit of 97 .

9^7=9 × 81 × 81 × 81 →

the units' digit is 9 .

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