Question

The dinner check for a birthday party was $89.50. How do you estimate a 15% tip?

Answer 1

`15%` of the bill is about `$13.50`

Explanation:

It is very easy to estimate `10%` of any number - just divide by 10 by moving the decimal point one place to the left.

Once you know `10%` of an amount, it is possible to find `5%` by dividing the value that is `10%` by 2. Adding these answers gives a quick estimate of `15%`

For example: "Find 15% of 300"

`10%` of 300 = 30 and `30 div 2 = 15`

15% of 300 = 30+15 =45

In the same way for this question ...

Treat `89.50` as `$90` Find 10%, then 5%.

`10% +5% = $9+%4.50 = $13.50`

`15%` of the bill is about `$13.50`