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NCERT Solutions for Class 8 Maths Chapter 12 : Exponents and Powers

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Chapter 12 : Exponents and Powers

12.1 Introduction

Do you know? Mass of earth is 5,970,000,000,000, 000, 000, 000, 000 kg. We have already learnt in earlier class how to write such large numbers more conveniently using exponents.

12.2 Powers with Negative Exponents

In general, we can say that for any non-zero integer a,We learnt how to write numbers like 1425 in expanded form using exponents as,Let us see how to express 1425.36 in expanded form in a similar way.

12.3 Laws of Exponents

We have learnt that for any non-zero integer a,where m and n are natural numbers. Does this law also hold if the exponents are negative? Let us explore.On the same lines you can verify the following laws of exponents, where a and b are non zero integers and m, n are any integers.

12.4 Use of Exponents to Express Small Numbers in Standard Form

Observe the following facts.
1. The distance from the Earth to the Sun is 149,600,000,000 m.
2. The speed of light is 300,000,000 m/sec.
3. Thickness of Class VII Mathematics book is 20 mm.
4. The average diameter of a Red Blood Cell is 0.000007 mm.
5. The thickness of human hair is in the range of 0.005 cm to 0.01 cm.
6. The distance of moon from the Earth is 384, 467, 000 m (approx).
7. The size of a plant cell is 0.00001275 m.
8. Average radius of the Sun is 695000 km.
9. Mass of propellant in a space shuttle solid rocket booster is 503600 kg.
10. Thickness of a piece of paper is 0.0016 cm.
11. Diameter of a wire on a computer chip is 0.000003 m.
12. The height of Mount Everest is 8848 m.



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