Question

Millie tries to work out the answer to 416 * 1.9 using the calculator.
She gets an answer of 7904.
a) Without using a calculator, estimate 416 * 1.9 by rounding each number to 1 significant figure. Is Millie's answer sensible?
b) Use a calculator to work out the actual answer. Use this to explain what Millie may have done wrong.

Answer 1

a) To estimate 416 * 1.9, we can round 416 to 400 and 1.9 to 2. The calculation then becomes 400 * 2 = 800. Millie's answer of 7904 is not sensible as it is much larger than the estimated answer of 800.

b) Using a calculator, the actual answer to 416 * 1.9 is 790.4. Millie may have accidentally added an extra zero to her answer, resulting in 7904 instead of 790.4.