RD Sharma solution class 8 chapter 2 Powers Exercise 2.3

Exercise 2.3

Page-2.22



Question 1:

Express the following numbers in standard form:
(i) 6020000000000000
(ii) 0.00000000000943
(iii) 0.00000000085
(iv) 846 × 107
(v) 3759 × 10−4
(vi) 0.00072984
(vii) 0.000437 × 104
(viii) 4 ÷ 100000

Answer 1:

To express a number in the standard form, move the decimal point such that there is only one digit to the left of the decimal point.
(i) 6020000000000000 = 6.02 x 1015      (The decimal point is moved 15 places to the left.)
(ii) 0.0000000000943 = 9.43 x 10−12     (The decimal point is moved 12 places to the right.)
(iii) 0.00000000085 = 8.5 x 10−10     (The decimal point is moved 10 places to the right.)
(iv) 846 x 107 = 8.46 x 102 x 107 = 8.46 x 109     (The decimal point is moved two places to the left.)
(v) 3759 x 10−4 = 3.759 x 103 x 10−4 = 3.759 x 10−1     (The decimal point is moved three places to the left.)
(vi) 0.00072984 = 7.984 x 10−4     (The decimal point is moved four places to the right.)
(vii) 0.000437 x 104 = 4.37 x 10−4 x 104 = 4.37 x 100 = 4.37     (The decimal point is moved four places to the right.)
(viii) 4/100000 = 4 x 100000−1 = 4 x 10−5     (Just count the number of zeros in 1,00,000 to determine the exponent of 10.)


Question 2:

Write the following numbers in the usual form:
(i) 4.83 × 107
(ii) 3.02 × 10−6
(iii) 4.5 × 104
(iv) 3 × 10−8
(v) 1.0001 × 109
(vi) 5.8 × 102
(vii) 3.61492 × 106
(viii) 3.25 × 10−7

Answer 2:

(i) 4.83 x 107 = 4.83 x 1,00,00,000 = 4,83,00,000
(ii) 3.02 x 10−6 = 3.02/106 = 3.02/10,00,000 = 0.00000302
(iii) 4.5 x 104 = 4.5 x 10,000 = 45,000
(iv) 3 x 10−8 = 3/108 = 3/10,00,00,000 = 0.00000003
(v) 1.0001 x 109 = 1.0001 x 1,00,00,00,000 = 1,00,01,00,000
(vi) 5.8 x 102 = 5.8 x 100 = 580
(vii)  3.61492 x 106 = 3.61492 x 10,00,000 = 3614920
(viii) 3.25 x 10−7 = 3.25/107 = 3.25/1,00,00,000 = 0.000000325

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