Lesson: General GRE Math Strategies

Comment on General GRE Math Strategies

Tabish Badar's picture


the best!!!

I'm confused on the last problem. How do we know that there are 21 pairs that add to 65? Why is 53-12 relevant, and why does y-x+1 factor in?
greenlight-admin's picture

Once we know that we can rewrite the sum as a bunch 65's, we need to determine how many 65's there are to add. We do that using the formula y-x+1. For more on this, see the following video - https://www.greenlighttestprep.com/module/gre-word-problems/video/930

you are my god. i love you man. 

I've never had problems with math so I didn't think I needed any help with GRE math since it's basically high school math. But you've got some really nice tips here man. Thanks!

I find it more intuitive for this type of problem to find the average of the series and then multiply that by the number of values in the series to get the sum. For example, first add the first value in the series and the last value in the series and then divide the sum by 2. This gives me the average value (or middle value) of the series. In this case (12+53)/2 = 32.5. Then, I multiply this value by the number of values in the series to get the sum of the series.
greenlight-admin's picture

That's a perfectly valid approach!

Always Scan First!

Whenever you encounter a quantitative question with answer choices, be sure to SCAN the answer choices before performing any calculations. In many cases, the answer choices provide important clues regarding how to best solve the question. 

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