What is the value of 10^8 - 6^7?

Question

A. 99,720,064
B. 99,720,069
C. 99,721,022
D. 99,722,055
E. 99,723,097

pratikbais · Accepted Answer

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 ..

Bunuel · Answer

A little harder question testing the same concept: 10-126300.html Hope it helps.

PareshGmat · Answer

10^8  ends with 0;  6^7  ends with 6

Difference will provide 4 at the units place

Answer = A

Nunuboy1994 · Answer

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"

Abhishek009 · Answer

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...

JeffTargetTestPrep · Answer

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

Bismarck · Answer

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  10-6 = 4 , as  10^8>6^7 . 
Only Option A has 4 at unit's digit.

Omnoui · Answer

What is the value of 10^8 - 6^7?

10^8 is bigger than 6^7 so the unit digit of this difference will be 10-6=4 AS 10^8 ends in 0 and 6^7 ends in 6.

Correct answer A. 99,720,064

What is the value of 10^8 - 6^7?

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What is the value of 10^8 - 6^7?

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