Select and carry out calculations and round answers to the nearest significant figure. A way of approximating or estimating an answer is to round off using significant figures.
We can use significant figures to get an approximate answer to a problem.
We can round off all the numbers in a maths problem to \(1\) significant figure to make 'easier' numbers. It is often possible to do this in your head.
Question
Find a rough answer to \(\frac{{19.4}}{{0.0437}}\)
We first round off both numbers to \(1\) significant figure (\(s.f.\)):
\(19.4 = 20 (\,1\,s.f.)\)
\(0.0437 = 0.04 (\,1\,s.f.)\)
So we now need to make the denominator a whole number. We can do this by multiplying both \(20\) and \(0.04\) by \(100\).