Partial products · Alberta Grade 5 · maddyhelps.com
Multiply by the ones digit on the first row, then by the tens digit on the second — which starts with a zero in the ones place, because it is tens. Add the two rows. Estimate first.
Multiplying by two digits
234 × 16 = 1404 + 2340 = 3744; 305 × 24 = 1220 + 6100 = 7320; 418 × 35 = 2090 + 12540 = 14630; 527 × 42 = 1054 + 21080 = 22134; 136 × 58 = 1088 + 6800 = 7888; 609 × 71 = 609 + 42630 = 43239. A good estimate for 418 × 35 is 400 × 35 = 14 000; the answer, 14 630, is close.
The zero at the start of the second row is the step that goes missing. Without it, 234 × 16 comes out as 1404 + 234 = 1638 instead of 3744, and only an estimate will catch it.
Why this matters is on the numbers to a million page. More sheets