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exploringm
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What is the sum of all digits for the number 10^30 - 37 Updated on: 30 May 2024, 08:24
Originally posted by exploringm on 11 Feb 2013, 10:01.
Last edited by Bunuel on 30 May 2024, 08:24, edited 2 times in total.
Moved to PS forum.
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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35% (medium)

Question Stats:

67% (01:35) correct 33% (01:50) wrong based on 1173 sessions

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What is the sum of all digits for the number 10^30 - 37 ?

A. 63
B. 252
C. 261
D. 270
E. 337
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C
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Bunuel
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What is the sum of all digits for the number 10^30 - 37 11 Feb 2013, 10:15
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exploringm
What is the sum of all digits for the number 10^30 - 37 ?

A. 63
B. 252
C. 261
D. 270
E. 337

Edit: Sorry, I meant to have this in the PS sub-forum.
Show more

10^30 is a 31-digit number: 1 followed by 30 zeros.

10^30 - 37 is a 30-digit number: 28 9's and 63 in the end. Thus the sum of the digits is 28*9+6+3=261.

Answer: C.

Similar question to practice:
10-25-560-is-divisible-by-all-of-the-following-except-126300.html

Hope it helps.
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What is the sum of all digits for the number 10^30 - 37 06 Oct 2016, 12:39
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exploringm
What is the sum of all digits for the number 10^30 - 37 ?

A. 63
B. 252
C. 261
D. 270
E. 337
Show more

10^30 = 1000000...thirty 0's in total....000000
In other words, 10^30 is a 31-digit number.

So, for example, 10^30 - 1 is a 30-digit number.
In fact, 10^30 - 1 = 9999...thirty 9's in total...99999

Likewise, 10^30 - 37 is a 30-digit number.
Since 100 - 37 = 63, we know that 10^30 - 37 = 9999999.....9999963
Since 10^30 - 37 is a 30-digit number, we know that this value has 28 nines followed by 63
That is 100 - 37 = 999,999,999,999,999,999,999,999,999,963

The sum of all digits = (28)(9) + 6 + 3
= 261
=
Show Spoiler
C

Cheers,
Brent
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What is the sum of all digits for the number 10^30 - 37 06 Oct 2016, 12:32
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Bunuel
exploringm
What is the sum of all digits for the number 10^30 - 37 ?

A. 63
B. 252
C. 261
D. 270
E. 337

Edit: Sorry, I meant to have this in the PS sub-forum.

10^30 is a 31-digit number: 1 followed by 30 zeros.

10^30 - 37 is a 30-digit number: 28 9's and 63 in the end. Thus the sum of the digits is 28*9+6+3=261.

Answer: C.

Similar question to practice:
10-25-560-is-divisible-by-all-of-the-following-except-126300.html

Hope it helps.
Show more

Hello Bunuel,

How you are able to figure out that it will be having "28 9's and 63 in the end" ?

Thanks.
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What is the sum of all digits for the number 10^30 - 37 20 Nov 2019, 23:39
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Any number of the form \(10^n\) will have (n+1) digits viz a 1 followed by n zeroes. The first thing we can infer in this question, therefore, is the fact that \(10^{30}\) will have 31 digits – a 1 followed by 30 zeroes.

When 37 is subtracted from \(10^{30}\), the last 2 digits will be 63 and each of the remaining digits will be 9. Because we had to take a carry over, we will only be left with 30 digits now.
Therefore, 9 appears 28 times followed by a 6 followed by a 3. The sum of these digits = (28*9) + 6 + 3 = 261.
The correct answer option is C.

A question like you tests your knowledge of basic mathematical operations like subtraction, addition and multiplication and hence, the only mistakes that can happen on such questions are calculation mistakes. Therefore, be very careful while doing the calculations. Even if you spend 1 minute on this question, make sure that you get it right, else the algorithm may penalize you for having gone wrong with such simple questions.

Hope this helps!
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What is the sum of all digits for the number 10^30 - 37 21 Nov 2019, 03:54
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exploringm
What is the sum of all digits for the number 10^30 - 37 ?

A. 63
B. 252
C. 261
D. 270
E. 337

Show more
Sum of the digits = Number of 9's is 28 + 6 + 3
= (28*9) + 9
= 261

C is correct.
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What is the sum of all digits for the number 10^30 - 37 01 Apr 2023, 21:09
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What is the sum of all digits for the number 10^30 - 37 ?

A. 63
B. 252
C. 261
D. 270
E. 337

Solution:

10^2 - 37 = 63
10^3 - 37 = 963
10^4 - 37 = 9963
.
.
10^n - 37 = 9 (n-2 times) 63

So 10^30 - 37 = 9*28 + 6 + 3 = 261

Option C is correct
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What is the sum of all digits for the number 10^30 - 37 29 Jul 2025, 12:29
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