Writing numbers as Powers of 10

Chapter 13 Class 7 Exponents and Powers
Concept wise

From place value of numbers,

we know that

 Thousands Hundreds Tens Ones 2 4 8 6

We write the number as

2486 = 2 × 1000 + 4 × 100 + 8 × 10 + 6 × 1

= 2 × 10 3 + 4 ×10 2 + 8 × 10 1 + 6 × 10 0

So, we can write any number as power of 10

For number,

 Ten Thousands Thousands Hundreds Tens Ones 9 8 2 7 6

We write the number as

98276 = 9 × 10,000 + 8 × 1,000 + 2 × 100 + 7 × 10 + 6 × 1

= 9 × 10 4 + 8 × 10 3 + 2 × 10 2 + 7 × 10 1 + 6 × 10 0

For number,

 Tens Ones 2 8

We write the number as

28 = 2 × 10 + 8 × 1

= 2 × 10 1 + 8 × 10 0

For decimal number,

849.58

In place value table

 Hundreds Tens Ones Decimal Tenth Hundredth 8 4 9 . 5 8

So, we write the number as

849.58 = 8 × 100 + 4 × 10 + 9 × 1 + 5 × 1/10 + 8 × 1/100

= 8 × 10 2 + 4 × 10 1 + 9 × 10 0 + 5 × 1/10 1  + 8 × 1/10 2

= 8 × 10 2 + 4 × 10 1 + 9 × 10 0 + 5 × 10 -1 + 8 × 10 -2

For decimal number,

29.0008

In place value table

 Tens Ones Decimal Tenth Hundredth thousandth Ten Thousandt h 2 9 . 0 0 0 8

We write the number as;

29.0008 = 2 × 10 + 9 × 1 + 0 × 1/10 + 0 × 1/100 + 0 × 1/1000 + 8 × 1/10000

= 2 × 10 1 + 9 × 10 0 + 0 × 10 -1 + 0 × 10 -2 + 0 × 10 -3 + 8 × 10 -4

= 2 × 10 1 + 9 × 10 0 + 8 × 10 -4

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