Free Practice Question
PS · Problem Solving
655-705
Exponents/Powers
If the sum of the digits of equals , what is the value of y?
Answer Choices
Correct answer marked belowA
14
B
81
243
Correct
D
729
E
2187
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Explanation
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Official Explanation
Official
The sum of the digits of is equal to 3^7. The expression represents a number consisting of y digits, all of which are 9. Therefore, the sum of the digits is . We set this equal to : . Since , we can rewrite this as…
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Comments
3
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P
ParveenApr 26, 2025
Great
R
RockyMar 21, 2025
Tricky wording but good practice
U
UjjawalJan 17, 2025
cheers!
What this question tests
What it tests
Your grasp of exponent rules — multiplying and dividing powers, power-of-a-power, and negative/zero exponents.
Common trap
Adding exponents when multiplying bases that have the same exponent, or confusing (x^a)^b with x^(a·b).
Details
Difficulty
655-705
Type
PS
Category