Grade 4

Multiplying by one digit

The written method. Part of numbers to 10 000.

Multiplying by one digit

The written method · Alberta Grade 4 · maddyhelps.com

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Multiply the ones first, then the tens, then the hundreds, carrying as you go. Estimate first — 234 × 3 is about 200 × 3 = 600 — so an answer of 70 or 7000 can be caught at once.

234

× 3

406

× 5

157

× 4

328

× 6

519

× 7

245

× 8

My estimate for 519 × 7

For the grown-up

Multiplying by one digit

702, 2 030, 628, 1 968, 3 633, 1 960. A good estimate for 519 × 7 is 500 × 7 = 3500, and the answer, 3633, is close — which is the check.

The zero in 406 × 5 is the one that goes wrong: 5 × 0 tens is 0 tens, but the carry from the ones still has to be written in the tens column.

Why this matters is on the numbers to 10 000 page. More sheets