Work out estimation and approximation instantly with clear inputs, formula shown and shareable results.
Estimation rounds each value to a few significant figures before calculating, giving a quick sanity check. Comparing with the exact answer shows how much precision the shortcut costs.
Percentage error
100 × |exact − estimate| / |exact|
50 × 20 = 1000 against the exact 1037.31, a 3.6% error — close enough to catch a gross mistake.
It guards against slips of a factor of ten and gives a feel for whether a computed answer is plausible.