Grade: 4, Topic(s): multiplication/division

## Purpose

To multiply numbers by multiples of 10

None

Ask students to multiply two numbers, a single digit number and 10. After multiplying by 10 for a while, have them multiply by 20 and higher multiples of 10. It can be helpful to use sequences of related problems, such as 5 × 10, 5 × 20, 5 × 30. To keep students attentive, say the problem before choosing a student to give the result.

Part 1 has students multiplying a single digit number and 10. It might helpful to remind the class that 2 × 10 is really adding 2 tens. Part 2 multiplies single digit numbers by 20 and 30. The extension provides an opportunity for students to multiply single digit numbers by higher multiples of 10, such as 40, 50, and 60.

Let’s multiply single digit numbers by 10. Here we go!

Examples:

- 1 × 10 (10)
- 8 × 10 (80)
- 2 × 10 (20)
- 3 × 10 (30)
- 6 × 10 (60)
- 9 × 10 (90)
- 4 × 10 (40)

*While children are enjoying their building of mastery, feel free to repeat. When children eager for more, try Part 2.*

Now let’s multiply single digit numbers by 20 and 30.

Examples:

- 2 × 10 (20)
- 2 × 20 (40)
- 2 × 30 (60)
- 4 × 20 (80)
- 4 × 30 (120)
- 5 × 10 (50)
- 5 × 20 (100)
- 5 × 30 (150)

Now let’s multiply single digit numbers by 40, 50, and 60.

Examples:

- 2 × 40 (80)
- 2 × 50 (100)
- 2 × 60 (120)
- 4 × 50 (200)
- 4 × 60 (240)
- 5 × 40 (200)
- 5 × 50 (250)
- 5 × 60 (300)

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