Estimating

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

For example,

579 \times 41 =?

Now, 579 \approx 600 (correct to one significant figure); and 41 \approx 40 (again, one significant figure).

Therefore,

    \[579 \times 41 \approx 600 \times 40 = 24000\]

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


Done here – go back to the menu for Unit 1.