Round each value to 1 significant figure then perform the calculation (without a calculator).

For example,

?

Now, (correct to one significant figure); and (again, one significant figure).

Therefore,

Applets: Begin by rounding to one significant figure. Then adjust your answer. Aim for less than 10% error (good), or less than 5% error (excellent!)

## Up to 100 multiplied by 100

## A little more difficult