Exercise 10.2

1. Express the following numbers in standard form:

Instructions

(i) 0.0000000000085 = =

(ii) 0.00000000000942 = =

(iii) 6020000000000000 =

(iv) 0.00000000837 = =

(v) 31860000000 =

2. Express the following numbers in usual form.

Instructions

(i) 3.02 × 10−6 = 3.02106 =

(ii) 4.5 × 104 = 4.5 × =

(iii) 3 × 10−8 = 3108 =

(iv) 1.0001 × 109 =

(v) 5.8 × 1012 = 5.8 × =

(vi) 3.61492 × 106 = 3.61492 × =

3. Express the number appearing in the following statements in standard form.

Instructions

(i) 1 micron is equal to 11000000 m.

1 micron = 11000000 = =

(ii) Charge of an electron is 0.000,000,000,000,000,000,16 coulomb.

So, 0.000,000,000,000,000,000,16 = coulomb

(iii) Size of a bacteria is 0.0000005 m

So, 0.0000005 = = = m

(iv) Size of a plant cell is 0.00001275 m

0.00001275 = m

(v) Thickness of a thick paper is 0.07 mm

0.07 mm = mm = = mm

4. In a stack there are 5 books each of thickness 20mm and 5 paper sheets each of thickness 0.016 mm. What is the total thickness of the stack?

Instructions

Thickness of one book = mm. Thus, thickness of 5 books = 20 × = mm

Thickness of one paper = mm . Thus, thickness of 5 papers = 0.016 × = mm

Total thickness of a stack = + = mm

Total thickness of a stack (standard form) = × mm

We found the answer.

Chapter 10: Exponents and Powers