Prime Detective ↗
Identify the prime number among composite distractors.
Round a sum to the nearest ten using mental estimation.
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Round the total to the nearest ten. 84 + 24
the answer is 110. Add first, then round to the nearest multiple of ten.
Work out a rough answer before checking the options. If a result surprises you, use the explanation to identify the step you missed. Accuracy is more useful than rushing through a rule you have not understood.
This is a recreational numbers activity. Results describe performance on this particular task, with this device and these rules. They are not a clinical assessment, IQ score or promise of improvements in daily life. Your best result and recent sessions stay in this browser; no account is required.
Yes. You can play the full activity without a payment, download or account.
Use Tab to focus buttons and Enter or Space to activate them. Answer fields accept normal typing. The maze also supports arrow keys. Timed tests will differ between touch, mouse and keyboard input.
Practice, a different generated puzzle, distractions and input timing all affect results. Compare several sessions rather than drawing a conclusion from one attempt.