NCERT Book Class 7 Maths Chapter 11 Exponents and Powers

170 MATHEMATICS

Chapter 11
Exponents and
Powers

11.1 INTRODUCTION
Do you know what the mass of earth is? It is
5,970,000,000,000,000,000,000,000 kg!
Can you read this number?
Mass of Uranus is 86,800,000,000,000,000,000,000,000 kg.
Which has greater mass, Earth or Uranus?
Distance between Sun and Saturn is 1,433,500,000,000 m and distance between Saturn
and Uranus is 1,439,000,000,000 m. Can you read these numbers? Which distance is less?
These very large numbers are difficult to read, understand and compare. To make
these numbers easy to read, understand and compare, we use exponents. In this Chapter,
we shall learn about exponents and also learn how to use them.

11.2 EXPONENTS
We can write large numbers in a shorter form using exponents.
Observe 10, 000 = 10 × 10 × 10 × 10 = 104
The short notation 104 stands for the product 10×10×10×10. Here ‘10’ is called the
base and ‘4’ the exponent. The number 104 is read as 10 raised to the power of 4 or
simply as fourth power of 10. 104 is called the exponential form of 10,000.
We can similarly express 1,000 as a power of 10. Note that
1000 = 10 × 10 × 10 = 103
Here again, 103 is the exponential form of 1,000.
Similarly, 1,00,000 = 10 × 10 × 10 × 10 × 10 = 105
105 is the exponential form of 1,00,000
In both these examples, the base is 10; in case of 103, the exponent
is 3 and in case of 105 the exponent is 5.