Multiply a one-digit number by a multiple of ten, like 6 × 40, with ten-rods to see it by. Some questions hide a different number instead: ? × 30 = 210, or 7 × ? = 280.
The wrong choices are place-value slips: dropping the zero (24 for 6 × 40), adding an extra one (2,400), or answering in tens.
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