## Multiplication by 10s, 100s, 1000s

Practice Unlimited Questions

#### 1. Multiply 46 by 10.

Multiplying by 10

When you multiply a number by 10, the value of each of its digits increases ten times. Hence, the value of the whole number increases ten times.
46  ×  10
=  (40 + 6)  ×  10
=  (40  ×  10)  +  (6  ×  10)
=  400  +  60
=  460
Quite simply,
46  ×  10
=  46 tens
=  460

#### 2. Multiply 46 by 100.

Multiplying by 100

When you multiply a number by 100, the value of each of its digits increases hundred times. Hence, the value of the whole number increases hundred times.
46  ×  100
=  (40 + 6)  ×  100
=  (40  ×  100)  +  (6  ×  100)
=  4000  +  600
=  4600
Quite simply,
46  ×  100
=  46 hundreds
=  4600

#### 3. Multiply 46 by 1000.

Multiplying by 1000

When you multiply a number by 1000, the value of each of its digits increases thousand times. Hence, the value of the whole number increases thousand times.
46  ×  1000
=  (40 + 6)  ×  1000
=  (40  ×  1000)  +  (6  ×  1000)
=  40000  +  6000
=  46000
Quite simply,
46  ×  1000
=  46 thousands
=  46000

#### 4. If 430  ×  2 = 860, find the value of: a)  430  ×  20 b)  430  ×  200 c)  430  ×  2000

a)        430  ×  20
=  430  ×  2  ×  10
=  (430  ×  2)  ×  10
=  860  ×  10
=  8600
b)        430  ×  200
=  430  ×  2  ×  100
=  (430  ×  2)  ×  100
=  860  ×  100
=  86 000
c)        430  ×  2000
=  430  ×  2  ×  1000
=  (430  ×  2)  ×  1000
=  860  ×  1000
=  860 000

#### 5. Estimate the value of: a)  782  ×  23 b)  42  ×  9123

a)        782  ×  23
≈  800  ×  20
=  800  ×  2  ×  10
=  1600  ×  10
=  16 000
782  ≈  800
and
23  ≈  20
b)        42  ×  9123
≈  40  ×  9000
=  40  ×  9  ×  1000
=  360  ×  1000
=  360 000
42  ≈  40
and
9123  ≈  9000