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# Multiply Multiples

### Multiplying multiples of ten by multiples of ten

To solve 20 × 40, think (2 tens × 4) × 10 = ________ 20 × (4 × 10) = ________ 20 × 40 = _______ (2 tens × 4) × 10 = 8 tens x 10 20 × (4 × 10) = 20 x 80 20 × 40 = 800
At a concert venue, there are 40 seats per row. How many seats are in 90 rows? 40 x 90 = _____ 40 x 9 x 10 = ___ 360 x 10 = 3,600 There are 3,600 seats in 90 rows.
Rewrite the equation in unit form and solve. 20 × 20 = ________ 20 x 20 = ___ 2 tens x 2 tens = ___ 2 x 20 x 10 = ___ 40 x 10 = 400 20 x 20 = 400
Rewrite the equation in unit form and solve. 50 × 80 = ________ 50 x 80 = ___ 5 tens x 8 tens = ___ 5 x 80 x 10 = ___ 400 x 10 = 4,000 50 x 80 = 4,000
Rewrite the equation in unit form and solve. 60 × 90 = ________ 60 x 90 = ___ 6 tens x 9 tens = ___ 6 x 90 x 10 = ___ 540 x 10 = 5,400 60 x 90 = 5,400
Rewrite the equation in unit form and solve. 60 × 60 = ________ 60 x 60 = ___ 6 tens x 6 tens = ___ 6 x 60 x 10 = ___ 360 x 10 = 3,600 60 x 60 = 3,600
Rewrite the equation in unit form and solve. 80 × 30 = ________ 80 x 30 = ___ 8 tens x 3 tens = ___ 3 x 80 x 10 = ___ 240 x 10 = 2,400 80 x 30 = 2,400
Rewrite the equation in unit form and solve. 70 × 80 = ________ 70 x 80 = ___ 7 tens x 8 tens = ___ 7 x 80 x 10 = ___ 560 x 10 = 5,600 70 x 80 = 5,600

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