Directions
Let's review some tricks for doing math in your head:
- Round off. $44.75 becomes $45. Or, to make the math even easier, round up to $50.
- To calculate 10% of an amount, move the decimal point one place to the left. 10% of $50 (which is the same as $50.00) is $5.
- Double it and you get 20%. Triple it and you get 30%. Quadruple it and you get 40%. Get it?