Long multiplication breaks a hard calculation into easier ones. For 346 × 27, multiply 346 by 7, then multiply 346 by 20, and add the two results.
Write the numbers in columns. The first row is 346 × 7 = 2 422. For the second row, put a zero in the ones column, because you are multiplying by 2 tens, then work out 346 × 2 = 692 to give 6 920. Add the rows: 2 422 + 6 920 = 9 342. Estimate to check: 350 × 30 = 10 500, which is close.
Worked example
Work out 518 × 34
- 518 × 4 = 2 072 and 518 × 30 = 15 540.
- Add the two rows: 2 072 + 15 540.
Answer:17 612
Key words
- long multiplication
- multiplying by each digit, then adding the rows
- partial product
- one of the rows you add
- estimate
- a rounded answer to check with
Practise this
New questions every time.
Common Core-referenced: 5.NBT.B.5