Short multiplication

For grown-ups: this lesson in words

Years 3 to 6 · Maths

Short multiplication: I can multiply a number with up to 4 digits by a 1-digit number using short multiplication.

1. Here are 3 rows of 12 cupcakes. The first row has 12.

   Count in 12s for the next rows: 12, 24, 36.

   12 × 3 = 36

   Picture: An array of 3 rows of 12 cupcakes. The rows are counted in 12s: 12, 24 and 36.

2. 23 × 3 is not in our times tables. Here is 23 as 2 tens and 3 ones.

   Partition 23 into 20 and 3.

   20 × 3 = 60 and 3 × 3 = 9

   60 + 9 = 69, so 23 × 3 = 69

   Picture: Base 10 blocks showing 23: 2 tens and 3 ones. It is split into 20 and 3.

3. Now the written way. Write 23, and 3 underneath it in the ones column.

   Ones first: 3 × 3 = 9. Write 9 in the ones column.

   Tens: 2 × 3 = 6. Write 6 in the tens column.

   23 × 3 = 69

   Picture: 23 times 3 worked out as a short multiplication: the answer is 69.

4. Your turn: Here is 21 × 4, set out ready. Ones first, then tens. What is 21 × 4?

   Picture: 21 times 4 set out as a short multiplication, with an empty answer row.

   Choose one:

   • 25
   • 48
   • 84

   Answer

   The answer: 84

   Ones: 1 × 4 = 4. Tens: 2 × 4 = 8. So 21 × 4 = 84

   Picture: 21 times 4 worked out as a short multiplication: the answer is 84.

Words to know

multiply:

Find how many in equal groups. 3 lots of 12 is 12 × 3.

partition:

Split a number into its tens and ones: 23 is 20 and 3.

column:

Ones, tens, hundreds and thousands each have their own column.

carry:

When a column makes 10 or more, move the tens into the next column on the left.