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Can someone help me understand how to do this GRE Quant Question?


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Posted

What is the remainder when 13^17 + 17^13 is divided by 10?

PS: This is the 26th question in Chapter 13 of the 5lb Manhattan Prep Book (Pg 498)

Posted

Hint 1: The remainder when dividing by 10 is always the ones digit (i.e the last digit) of a number.

Hint 2: When you have crazy large numbers like this, you are rarely expected to actually calculate the entire number. Instead, look for a pattern in the part of the number you care about and then use that pattern to get your answer.

Posted

Wow this is interesting. So TakeruK, there is no proper answer? I am still confused with your answer, I am very sorry. :(

Newbie here, and I would like to be notified of the replies :)

 

Posted

13^17 will have 3 as the last digit and 17^13 will have 7 as the last digit and when they both are added will give you 0 at the units place. that's done now to get the remainder when divided by 10 you get unit digit as remainder, here 0 is the remainder the answer is 0. I hope i am right.

 

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