More GMAT Memorization: Factorials

I’ve posted before about memorizing prime numbers, squares & cubes, and fraction, decimal, and percent conversions.  Here’s one more thing you need to memorize for the GMAT test: Factorials. Factorials will show up in number properties and combinatorics questions.

The first time during my GMAT study I came across a number with an exclamation point behind it, I could swear I had never seen that notation before.  I probably learned about factorials in elementary school and never revisited the subject after.  (Which kind of makes me wonder how relevant it will be during business school…)

Anyway, it’s recommended that you memorize at least up to ten, which is really not hard to do.  If you need to go further up, you can just do the math to get there.

11! = ?

10! x 11 = ?

3,628,800 x 11 = ?

(3,628,800 x 10) + (3,628,800 x 1) = ?

36,288,000 + 3,628,800 = 39,916,800

Image Source: Wikipedia

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