Multiplication and division
Multiplication
Multiplying finds the total when you have equal groups. An array shows this clearly as rows and columns.
How to multiply bigger numbers
1. Estimate first (round each number) to check your answer later. 2. To multiply by a 2-digit number, split it into tens and ones. 3. Multiply by each part, then add the answers together.
Worked examples
By a 1-digit number: 400 × 9
- Estimate: 400 × 10 = 4000.
- 4 × 9 = 36, then add the two zeros.
Answer: 400 × 9 = 3600
By a 2-digit number: 56 × 27
- Estimate: 60 × 30 = 1800.
- Split 27 into 20 and 7: 56 × 20 = 1120 and 56 × 7 = 392.
- Add the two answers: 1120 + 392 = 1512.
Answer: 56 × 27 = 1512
Where you see this in real life
- Working out the total mass of many identical boxes.
- Counting tins packed in trays and boxes in a warehouse.
- How many times a hummingbird beats its wings in a minute.
Key words
- Product
- The answer when two or more numbers are multiplied together. For example, the product of 3 and 5 is 15.
- Estimate
- A sensible guess of about how big an answer should be.
- Array
- Objects arranged in equal rows and columns.