Doing "back of the napkin" calculation for a new business
If so, this is the Web site for you. Math is full of simple tricks that, once mastered, allows you to do seemingly complex math without reaching for an adding machine.
This Week's Top Performers
DoItInYourHead.com is many things: mental math, arithmetics, math games, math training, remedial math practices. It is also ideal for: getting rid of the calculator, doing math without a calculator, doing math in your head, practice doing math in your head. This is a free service and does not cost you a penny