Multiply by Tens
4 × 30 is 4 × 3 tens
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How do you do 4 × 30 in your head? Ten-rods line up in an array where each rod is worth 10: count how many tens first, then turn them into the total. Answer from three choices — if you pick the answer that dropped a ten, the feedback tells you exactly what went wrong.
Don't grind out 4×30: first work out 4×3=12, then 12 tens make 120. Watch the rows of ten-rods and get the answer in two easy steps.