Don't calculate. Estimate — and be closest.
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You get a calculation and four candidate answers, only one of which is in the right ballpark. Working it out exactly is possible but slow; rounding both numbers and comparing magnitudes is much faster and gets you there just as reliably.
Estimation is the most undervalued numeracy skill. It is what tells you a bill is wrong, a statistic is implausible or a calculator entry has slipped a digit — and none of that requires an exact answer.
This version: Estimate a quotient. Your best score is saved in this browser, so you can come back and try to beat it. Nothing is uploaded and no sign-up is needed.
No. The wrong options are far enough apart that a guess is unlikely to land, but close enough that careless rounding will.
Round each number to one significant figure, calculate with those, then sanity-check the magnitude. 48 × 21 becomes 50 × 20, which is 1,000 — close enough to pick the right option.
Considerably. Estimating first and computing second catches the kind of slip that turns a correct method into a wrong mark.