Grade 3 · Unit 1: Number and place value

Multiplying 2-digit numbers

Split it into tens and ones.

Rows of seats

A bus has 14 rows with 4 seats in each. How many seats? Estimate: 10 × 4 = 40, so a bit more than 40.

Splitting the array

Split 14 into 10 and 4. 4 × 10 = 40 and 4 × 4 = 16. 40 + 16 = 56 seats.

The grid method

Write the tens and ones across the top. Multiply each part: 20 × 6 = 120, 3 × 6 = 18. Add the partial products: 120 + 18 = 138.

Check it makes sense

23 is between 20 and 25. 20 × 6 = 120 and 25 × 6 = 150. 138 is between them – good!

Bigger multiplications

The grid method works for bigger numbers too. Split 124 into 100, 20 and 4; split 23 into 20 and 3. Multiply each pair, then add: 2852.

What I learnt

• I can multiply a 2-digit number by a 1-digit number.
• I can use the grid method.