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Chapter 12 Exponents and Powers Exercise 12.2

Question 1.
Express the following numbers in standard form:
(i) 0.0000000000085
(ii) 0.00000000000942
(iii) 6020000000000000
(iv) 0.00000000837
(v) 31860000000
Solution:
NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Q1

NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Q1.1
(v) 31860000000
= 3.186 × 10000000000
= 3.186 × 1010
Hence, the required standard from = 3.186 × 1010

Question 2.
Express the following numbers in usual form.
(i) 3.02 × 10-6
(ii) 4.5 × 104
(iii) 3 × 10-8
(iv) 1.0001 × 109
(v) 5.8 × 1012
(vi) 3.61492 × 106
Solution:
NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Q2

NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Q2.1


Solution:
NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Q3

NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 Q3.1

Question 4.
In a stack there are 5 books each of thickness 20 mm and 5 paper sheets each of thickness 0.016 mm. What is the total thickness of the stack?
Solution:
Thickness of books = 5 × 20 = 100 mm
Thickness of 5 paper sheets = 5 × 0.016 mm = 0.080 mm.
Total thickness of the stack = 100 mm + 0.080 mm = 100.080 mm = 1.0008 × 102 mm

NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 q-1
NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 q-2
NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 q-3
NCERT Solutions for Class 8 Maths Chapter 12 Exponents and Powers Ex 12.2 q-4
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