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What is the value of 10^8  6^7?
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27 Feb 2012, 09:11
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What is the value of 10^8  6^7? A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097
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Re: What is the value of 10^8  6^7?"
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27 Feb 2012, 09:18
Answer A
As 10^n will always have last digit as 0 AND 6^n will always as last digit 6.. hence difference of such sum should always be ending with "4" and there is only on option ..



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Re: What is the value of 10^8  6^7?
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27 Feb 2012, 09:34
domu904 wrote: What is the value of 10^8  6^7?
A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097 A little harder question testing the same concept: 10126300.htmlHope it helps.
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Re: What is the value of 10^8  6^7?
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12 Aug 2014, 18:39
domu904 wrote: What is the value of 10^8  6^7?
A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097 \(10^8\) ends with 0; \(6^7\) ends with 6 Difference will provide 4 at the units place Answer = A
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Re: What is the value of 10^8  6^7?
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19 Jun 2017, 10:50
domu904 wrote: What is the value of 10^8  6^7?
A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097 We can attack this question a bit differently using some properties Rule 1 10^n power = 1 with n amount of zeros... 10^2 is 100 (2 zero) 10^5 100,000 (five zero) so 100000000 6^7 Rule 2 What is unit digits of 6? 6 is a special number 6^n will always have a units digit of 6 so the units digits of the answer must be 4 Thus "A"



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Re: What is the value of 10^8  6^7?
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19 Jun 2017, 10:58
domu904 wrote: What is the value of 10^8  6^7?
A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097 \(10^8\) Will have units digit as 0 \(6^7\) Will have units digit as 6 Now, \(10^8  6^7\) will have units digit as \(0  6 = 4\) Among the given options only (A) satisfies, so that is the answer...
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Re: What is the value of 10^8  6^7?
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06 Jul 2017, 17:40
domu904 wrote: What is the value of 10^8  6^7?
A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097 Since we know that the GMAT would not expect us to carry out the computation of the exact value of 10^8  6^7, we can focus on the units digits of the resulting difference. When we raise 10 to any power, the units digit of the answer is always 0. For example, 10^2 = 100 and 10^4 = 10,000. Similarly, the units digit of 6 raised to any power is 6. For example, 6^2 = 36, 6^3 = 216, etc. In this problem, the units digit of 10^8 will be 0 and the units digit of 6^7 will be 6. Thus, subtracting 6 from 10 (after 0 “borrows” a 1 from the tens digit) will result in a units digit of 4. Therefore, 10^8  6^7 must be equal to 99,720,064 since that is the only answer choice with a units digit of 4. Answer: A
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Re: What is the value of 10^8  6^7?
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22 Aug 2018, 10:20
domu904 wrote: What is the value of 10^8  6^7?
A. 99,720,064 B. 99,720,069 C. 99,721,022 D. 99,722,055 E. 99,723,097 OA:A Unit digit of \(10^8\) is \(0\) and unit digit of \(6^7\) is \(6\), Unit digit of expression \(10^8  6^7\) will be \(106 = 4\), as \(10^8>6^7\). Only Option A has 4 at unit's digit.




Re: What is the value of 10^8  6^7?
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