Times and divide with bigger numbers

What this chapter teaches

Times 10 moves every digit one place left. To multiply or divide a bigger number, split it into parts you know: 23 × 4 is 20 × 4 plus 3 × 4. A common mistake is writing the two small answers side by side, as 8 and 12 make 812.

Three questions to ask

There is no one right wording. Listen for the idea.

1. What happens to the digits of 27 when you times it by 10?
2. How could you work out 23 × 4 by splitting 23 into parts?
3. How can you tell that 812 is far too big for 23 × 4?

After the chapter, the learner can

• Multiply by 10 and 100 and see how the digits move
• Multiply numbers like 23 × 4 on paper
• Divide numbers like 84 ÷ 4 on paper