Definitive list of all the mental math you need to be able to do for the MCAT and how?

[cryhavoc]

I just need help. Problems keep coming up I can't do without a calculator and I don't want to be surprised on test day.

I have no idea how to do a lot of the mental math, too used to a calculator. Not even sure how to do a "log" in my head.

A guide/explanation page or source of all you need would be greatly appreciated.

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[ayocaptain628]

great question

 

[jamcat]

It's hard to write a concise summary, but most of the prep companies have a portion of a review book dedicated specifically to this. I know TPR has it in the back of their Physics book. EK combines their math section with their Verbal book. I'm pretty comfortable with the math so haven't really used it but I just did a quick flip through and it seems to cover all of the math you would need. I suggest finding TPR Physics or EK Verbal for a thorough guide if you're struggling. Good luck!

 

[FCMike11]

When I was studying for my MCAT I memorized sin/cos/tan for the angles 15/30/45/60/90. This definitely came in handy. Other users mentioned the books will have dedicated sections, which is true, especially tbr. Most of your math will be determined on ability to do it quickly, by estimation.

 

[texan2414]

Definitely know how to express values in scientific notation. Memorizing a couple logs shouldn't be that bad either.

Know approx value of sqrt (2)/2 and sqrt (3)/2. I'll post more later but if you have TBR books, there are some amazing mental math calculation shortcuts, etc.

 

[Cawolf]

The only thing I have found I needed to learn was how to calculate logs.

It is pretty easy and all you need to memorize is the log of 2 and 3.

Log 2 is about 0.3 and log 3 is about 0.48.

Then using the rules that log (x*y) = log x + log y

and log (x/y) = log x - log y

So then if you have a complicated log you can manipulate it to get the correct answer.

Such as we need pH and the [H+] = 0.0006

We know pH = -log [H+] = -log (0.0006)

Then you can make it -log(6 * 10^-4) = -log(6) - log(10^-4) = -[log(3) + log(2)] + 4 = -0.3 - 0.48 +4 = 3.22

I love that manipulation!