Week 5 – Jss 1 First Term General Mathematics Lesson Notes

WEEK 5    FRACTIONS (CONVERTION FROM PERCENTAGE TO DECIMAL AND DECIMAL TO FRACTION)

CONTENT: To convert a fraction into a decimal, first rewrite the numerator as a decimal, then divide it by the denominator.
Example 1 (a) change into a terminating decimal number (b) to decimal fraction
Solution:

1. Numerator 3 can be written I decimal number as 3.0 or 3.00 0r 3.000

= 0.75 I,e 4 divide 3, then add zero, 4 goes in 30 is ,it remain 2, add 0 to make it 20 and 4 in 20 gives 5
Therefore = 0.75

1. 8 divies 5,it becomes 0,then add zero to make it 50,it gives 6, it remains 2, add zero it becomes 20, 8 divides 20 is 2, it remains 4, add zero to gives 40, 8 in 40 is 5

Therefore = 0.625.
CONVERTING DECIMALS TO FRACTIONS
To change a decimal into a fraction, count the digits after the decimal, then divide by the appropriate power of 10,i.e 10,100,1000.
Example : convert each of the following decimal numbers into a fraction in lowest term:

1. 0.067 (b) 0.64

Solution
(a) 0.067 = (3 digits after the decimal point i.e divide by 1000)
(b) 0.64 = (as above information) divide through by 4 =
CONVERTING PERCENTAGE TO FRACTIONS
PERCENTAGE IS A SPECIAL TYPE OF FRACTION WITH 100 AS DENOMINATOR. THUS, TO CHANGE A PERCENTAGE TO A FRACTION, DIVIE BY 100.(%)
Example 1: express each of the following as a fraction in its simplest form:

1. 30% (b) 45% (c) 16 1/2 %

Solution

1. 30% = 30/100 i.e the zeros cancel each other. the answer is 3/10
2. 45% = 45/100 i.e 5 divide both it gives 9 / 20.
3. 16 ½ = 39/200 i.e you change the mixed number to improper fraction and then multiply it by %.