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What is the sum of the digits of integer x, where x = 4^10 x
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05 Nov 2017, 01:34
05 Nov 2017, 01:34
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What is the sum of the digits of integer x, where \(x = 4^{10} * 5^{13}\)?
(A) 13
(B) 11
(C) 10
(D) 8
(E) 5
Kudos for correct solution.
(A) 13
(B) 11
(C) 10
(D) 8
(E) 5
Kudos for correct solution.
Re: What is the sum of the digits of integer x, where x = 4^10 x
[#permalink]
05 Nov 2017, 06:23
05 Nov 2017, 06:23
1
We can rearrange the expression for x as \(2^7*(2*5)^{13}\) so that \((2*5)^{13}\) is equal to 1 followed by 13 zeros so that when it is multiplied by any number is equal to that number followed by 13 zeros. Then, \(2^7 = 128\) so that multiplied by the power of 10 becomes 128 and 13 zeros. Since we have to sum the digit of this number, we get 1+2+8+13*0 = 11.
Answer B
Answer B
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Re: What is the sum of the digits of integer x, where x = 4^10 x
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09 Jan 2018, 10:17
09 Jan 2018, 10:17
Expert Reply
Bunuel wrote:
What is the sum of the digits of integer x, where \(x = 4^{10} * 5^{13}\)?
(A) 13
(B) 11
(C) 10
(D) 8
(E) 5
(A) 13
(B) 11
(C) 10
(D) 8
(E) 5
We can simplify the given equation:
x = 4^10 x 5^13
x = 2^20 x 5^13
x = 2^7 x 2^13 x 5^13
x = 2^7 x 10^13
x = 128 x 10^13
We see that x is the number 128 followed by 13 zeros. Thus, the sum of the digits of x is 1 + 2 + 8 = 11.
Answer: B
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Re: What is the sum of the digits of integer x, where x = 4^10 x
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22 Jun 2023, 23:28
22 Jun 2023, 23:28
Hello from the GRE Prep Club BumpBot!
Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
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Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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