Multiplication by 10s, 100s, 1000s

Practice Unlimited Questions

Concepts Explained

1. Multiply by 10.

2. Multiply by 100

3. Multiply by 1000

4. Estimating Values

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