Question: Multiples of 5

Comment on Multiples of 5

Can you also solve by lining up 5 10 .... 200 and then another line 200 195... etc underneath and realize there are 40 of those numbers under 201 (200/5 = 40) that add up to be 205, then do 205*40 divided by 2 to get 4100?
gmat-admin's picture

Perfect! That's similar to the strategy described here:

Why is it not necessary to specify that only integer multiples are meant?
Thanks a lot and best
gmat-admin's picture

Great question!

From the Official Guide for GMAT Review: If x and y are integers and x ≠ 0, then x is a divisor (factor) of y provided that y = xn for some integer n.
In this case, y is also said to be divisible by x or to be a multiple of x.

So, the definition of "multiple" implies that we are dealing with integers only.

sir why not use ap instead?
gmat-admin's picture

I'm not a big fan of having students memorizing too many formulas. I feel that the test-makers can easily exploit some students' tendency to have an overly formulaic approach to GMAT math questions.


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