### Bookshelf

 Total GMAT Math Jeff's complete Quant guide, on sale now!
 Total GMAT Verbal Everything you need to ace GMAT Verbal!

1,800 Practice Math Questions

GMAT Official Guide, with IR
OG Math | OG Verbal
OG12 & Quant Rev solutions!

GMAT Question of the Day
Beginner's Guide to the GMAT
GMAT Hacks Affiliate Program

## Video: Mental Math: Percents

###### July 29, 2010

 You should follow me on Twitter. While you're at it, take a moment to subscribe to GMAT Hacks via RSS or Email.

Today's video covers one of my favorite mental math tricks: calculating percents by starting with 10%, 5%, and 1%. It's powerful, and it's a great way to get you thinking more abstractly about all sorts of calculations--not just percents.

Some of the subjects covered in the video overlap with something I wrote several years ago. So if you prefer the text version, or you'd like to have it handy for review after watching, click here.

About the author: Jeff Sackmann has written many GMAT preparation books, including the popular Total GMAT Math, Total GMAT Verbal, and GMAT 111. He has also created explanations for problems in The Official Guide, as well as 1,800 practice GMAT math questions.

 Total GMAT Math The comprehensive guide to the GMAT Quant section. It's "far and away the best study material available," including over 300 realistic practice questions and more than 500 exercises! Click to read more.