Https://www.gregmat.com/content/im-overwhelmed-arithmetic-progress-quiz-7-solutions

GRE Quant Problem Solving
1

https://www.gregmat.com/content/im-overwhelmed-arithmetic-progress-quiz-7-solutions

Can check the explanation for question 1 and 2 ? I found it very confusing!!
For Q1, he says that we have check the distance of units digit from the nearest multiple.

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image1905Ă—1007 121 KB

But then for Q2 the nearest multiple ends in a 0, so shouldnt the distance be 1 ???

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image1685Ă—865 109 KB

2

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image583Ă—1343 68.4 KB

You can just list powers of 7 and compute the remainder when divided by 5 to find some kind of “recurring pattern”. As evident from the image, if n is a non-negative multiple of 4, then 7^n will leave a remainder of 1 when divided by 5.

The same logic extends to the second question too.

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