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.
Observe that there are few numbers which we can read like 2 cm, 8848 m, 6,95,000 km. There are some large numbers like 150,000,000,000 m and some very small numbers like 0.000007 m. Identify very large and very small numbers from the above facts and write them in an adjacent table. We have learnt how to express very large numbers in standard form in the previous class. For example: 150,000,000,000 = 1.5 ×
Drop the very large numbers and very small numbers into the concerned boxes.
150,000,000,000 m
0.000007 m
110,000,000,000 m
0.000001 m
0.000003 m
130,000,000,000 m
0.000004 m
140,000,000,000 m
Very large numbers
Very small numbers
Now, let us try to express 0.000007 m in standard form.
Similarly, consider the thickness of a piece of paper which is 0.0016 cm.
Therefore, we can say thickness of paper is 1.6 × 10 − 3
TRY THESE
1. Write the following numbers in standard form.