Sizu Riatto
Book 1 · Everyday Math

Mental-Math Drill

A short timed round of shortcut-friendly problems — 2-digit × 1-digit, ×10 and ×100, 10% of a number, doubling and halving. Answer as many as you can before the clock runs out.

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Pick a length and press Start round. Type each answer and press Enter (or press the Submit button).
From the book — Chapter 3. The shortcuts you drill here — moving the decimal for ×10, halving to find 5%, doubling one side and halving the other — are how mental math really works. It's not memorising more facts, it's using a few tricks over and over.

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