Hardest Math tests

Hello all,

I've been looking through the posts trying to figure out if some of the GMAT Club math tests are harder than others, since I probably have time to take 10-15 of them and would like to take the hardest of the bunch.

It seems that the official answer is that the tests are not ordered in a specific way, so I was thinking I'd start with the tests that contain the "Hardest Questions" (m13, m14, m17-m24). I think I also saw some members mention that m5-m7 are on the harder side, so I'll give those a shot as well.

If anyone has any insight on the matter, I'd be very grateful to hear your thoughts! Which were the hardest 10-15 math tests in your opinion/experience?

(As a side note, if anyone has an opinion about the Verbal tests, I'd be grateful to hear those too - which ones were the hardest of the 6? --)

Thanks!