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M16-36

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M16-36 [#permalink]

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66% (00:49) correct 34% (00:51) wrong based on 76 sessions

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Official Solution:

What is the sum of digits in decimal notation of number \(10^{20} - 16\) ?

A. 158
B. 162
C. 165
D. 174
E. 183


\(10^{20}\) has 21 digits: 1 followed by 20 zeros;

\(10^{20}-16\) has 20 digits: 18 9's and 84 in the end;

So, the sum of the digits of \(10^{20}-16\) equals to \(18*9+8+4=174\).


Answer: D
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Re: M16-36 [#permalink]

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New post 07 Nov 2014, 06:38
Bunuel wrote:
Official Solution:

What is the sum of digits in decimal notation of number \(10^{20} - 16\) ?

A. 158
B. 162
C. 165
D. 174
E. 183


\(10^{20}\) has 21 digits: 1 followed by 20 zeros;

\(10^{20}-16\) has 20 digits: 18 9's and 84 in the end;

So, the sum of the digits of \(10^{20}-16\) equals to \(18*9+8+4=174\).


Answer: D
Just one comment or perhaps it is my ignorance but I got confused by the text in decimal notation

They could had just written What is the sum of digits of number XXXXXXXXXXX?

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Re: M16-36 [#permalink]

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New post 07 Nov 2014, 06:54
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mayankpant wrote:
Bunuel wrote:
Official Solution:

What is the sum of digits in decimal notation of number \(10^{20} - 16\) ?

A. 158
B. 162
C. 165
D. 174
E. 183


\(10^{20}\) has 21 digits: 1 followed by 20 zeros;

\(10^{20}-16\) has 20 digits: 18 9's and 84 in the end;

So, the sum of the digits of \(10^{20}-16\) equals to \(18*9+8+4=174\).


Answer: D
Just one comment or perhaps it is my ignorance but I got confused by the text in decimal notation

They could had just written What is the sum of digits of number XXXXXXXXXXX?


Based 10 notation, or decimal notation, is just a way of writing a number using 10 digits: 1, 2, 3, 4, 5, 6, 7, 8, and 0 (usual way), in contrast, for example, to binary numeral system (base-2 number system) notation.

Similar questions to practice:
the-sum-of-all-the-digits-of-the-positive-integer-q-is-equal-126388.html
the-sum-of-the-digits-of-64-279-what-is-the-141460.html
what-is-the-sum-of-all-digits-for-the-number-147057.html
10-25-560-is-divisible-by-all-of-the-following-except-126300.html
if-x-is-a-positive-integer-and-10-x-74-in-decimal-notation-61013.html

Hope it helps.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

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Re: M16-36 [#permalink]

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New post 01 Oct 2017, 23:22
Please explain - 10^20-16 has 20 digits: 18 9's and 84 in the end

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Re: M16-36 [#permalink]

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New post 01 Oct 2017, 23:31

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Re: M16-36 [#permalink]

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New post 01 Oct 2017, 23:38
yea it definitely helped. Thanks a lot.

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Re: M16-36   [#permalink] 01 Oct 2017, 23:38
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