Maths FROM 2

A fraction can be expressed as an equivalent fraction with denominator which is 10 or a power of 10

Ex: a)1/5 = 2/10 b) 1/8 = 125/1000 = 125/103

Definition

A fractions whose denominator is 10 or a power of 10 is called a decimal fraction, ex: 1/10, 1/102,1/103, etc…

As a decimal;

a)1/10 = 0.1 b)1/102 = 0.01 c) 2/103 = 0.002

Note that in base 10, the number 2634 means 2*10³ + 6*10² + 3*10¹ + 4*10⁰= 2*1000 + 6*100 + 3*10 + 4*1

Ex: express the following as a decimal fraction a) 1334, b) 1158

Solution: a) 1334 = 13 + 3/4= 13 + 75/100 = 13 + 75/10² = 1375102

b) 1158 = 11 + 5/8 = 11 + 625/1000 = 11 + 625/10³ = 11625103

Converting fractions to decimal

Ex: convert the following fractions to decimals a)3/4, b)413

Solution: a) 0.75 b) 0.33

4 30 4 + 3 10

28 9

20 10

20 9

= 0.75 = 4.333⁺

Converting from decimal to fraction

Ex: convert to fraction a)0.001, b)3.25

Solution: a) 0.001 = 1/1000 b)3.25 = 3 + 0.25 = 3 + 25/100 = 3 + 1/4 = 314

Multiplication and division of decimals

Ex: evaluate

a) 0.003 * 10000 = 0.003 * 10⁴ = 0.0030 = 30

b) 20.87 * 0.0005 = 2087 * 5 = 10435 = 0.010435 = 0.010435

c) 423.375 / 100 = 423.375 = 4.23375

d) 13.488 / 5.62 = 13.488*1005.62*100 = 1348.8/562 = 2.4 = 2.4

562 1348.8

1124

2248

par Claude Foumtum

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