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(integer) What is the remainder when 7^442 is divided by 10?

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(integer) What is the remainder when 7^442 is divided by 10?

by Max@Math Revolution » Thu Sep 22, 2016 4:20 pm
(integer) What is the remainder when 7442 is divided by 10?
A. 1 B. 3 C. 5 D. 7 E. 9
Last edited by Max@Math Revolution on Sat Sep 24, 2016 9:23 pm, edited 1 time in total.
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by Brent@GMATPrepNow » Fri Sep 23, 2016 4:50 am
Max@Math Revolution wrote:(integer) What is the remainder when 7442 is divided by 10?
A. 1 B. 3 C. 5 D. 7 E. 9
Are you sure you've correctly transcribed the question? As it stands, the correct answer is 2

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by regor60 » Fri Sep 23, 2016 7:33 am
I guess it could 1 since 2/10 reduces to 1/5
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by Max@Math Revolution » Sat Sep 24, 2016 9:23 pm
==> From, ~71=~7, ~72=~9, ~73=~3, ~74=~1, the first digit has a cycle of ^4 in the order of 7-->9-->3-->1-->7. If so, from 442=4*110+2 you get the remainder of 2, and you get 7442=74*110+2=~72=~9. Hence, the answer is E.
Answer: E

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
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by Brent@GMATPrepNow » Sun Sep 25, 2016 7:06 am
Max@Math Revolution wrote:==> From, ~71=~7, ~72=~9, ~73=~3, ~74=~1, the first digit has a cycle of ^4 in the order of 7-->9-->3-->1-->7. If so, from 442=4*110+2 you get the remainder of 2, and you get 7442=74*110+2=~72=~9. Hence, the answer is E.
Answer: E

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
Once you post a question/reply, you might consider checking the post to ensure that the formatting is correct.
I believe that 71, 72, 73 etc are meant to be expressed as 7^1, 7^2, 7^3 etc

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by regor60 » Sun Sep 25, 2016 12:41 pm
Max@Math Revolution wrote:==> From, ~71=~7, ~72=~9, ~73=~3, ~74=~1, the first digit has a cycle of ^4 in the order of 7-->9-->3-->1-->7. If so, from 442=4*110+2 you get the remainder of 2, and you get 7442=74*110+2=~72=~9. Hence, the answer is E.
Answer: E

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
Once again, and I'm not trolling, you've posed an improperly expressed problem.

In other words, this isn't the first time.

You hold yourself out as a math "expert", but your expertise seems to lie in wasting people's time.
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by regor60 » Sun Sep 25, 2016 12:41 pm
mm
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