Multiply by a multiple of ten using place value (Copy)

Multiply by a Multiple of Ten Using Place Value

When you multiply by 10, 20, 30, 40…, you can use place value to make it easy.

Key idea

A multiple of ten is (a number) × 10.

So:

• 20 = 2 × 10

• 50 = 5 × 10

• 80 = 8 × 10

Steps

1. Multiply by the non-zero digit (2, 5, 8, etc.)

2. Then add one zero (because of the ×10)

Examples

1) 7 × 30

30 = 3 × 10
7 × 30 = 7 × (3 × 10)
= (7 × 3) × 10
= 21 × 10
= 210

2) 9 × 40

9 × 4 = 36 → add one zero → 360

3) 6 × 70

6 × 7 = 42 → add one zero → 420

Quick practice (answers included)

1. 8 × 20 = 160

2. 5 × 60 = 300

3. 3 × 90 = 270

4. 7 × 50 = 350

5. 4 × 80 = 320