Good question. Thanks for posting.wishkaro wrote:What is the sum of all the digits in the number 9^27-27?
A. 81 B. 24 C. 28 D. 92 E. 100
OA [spoiler] A
9(9^26 – 3)
Sum of digits is always a multiple of 9. So A.[/spoiler]
sum of all the digits
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Vemuri
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9^27 results in a number which is a multiple of 9 and whose recursive sum of digits should be equal to 9.
27 is again a multiple of 9.
From my observation,
Any number which is a multiple of 9, has recursive sum of digits summed up to 9.
and
When a multiple of 9 is subtracted from another multiple of 9, the result is always a multiple of 9.
Since, the result is again a multiple of 9, from observation 1, only option A satisifies and matches my observation.
Thus, I conclude the answer to be A.
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Hope, it helps.
27 is again a multiple of 9.
From my observation,
Any number which is a multiple of 9, has recursive sum of digits summed up to 9.
and
When a multiple of 9 is subtracted from another multiple of 9, the result is always a multiple of 9.
Since, the result is again a multiple of 9, from observation 1, only option A satisifies and matches my observation.
Thus, I conclude the answer to be A.
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Hope, it helps.
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satish.nagdev
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99 isn't given in answer choices !!!avenus wrote:agree with the reasoning, but there's something wrong with this question:
9^27 - 27= 58 149737 003040 059690 390142
Sum of digits is 99, not 81
Wounded by GMAT but not dead
