Fractions
- A fraction is part of a whole and is shown by writing one whole number, the numerator, above another, the denominator.
- A fraction can be converted into a decimal by dividing the numerator by the denominator.
- Fractions and decimals can also be converted to percentages.
Converting fractions to decimals
Fractions can be converted into decimals by dividing the numeratorNumber written at the top of a fraction. The numerator is the number of parts used. Eg, for 1⁄3, the numerator is 1 by the denominatorNumber written on the bottom of a fraction. The denominator is the number of equal parts. Eg, for 1⁄3, the denominator is 3 using short division.
\( \frac {3}{8} = 3 \div 8 \)
\(\require{enclose}8\overset{\Large0.375}{\enclose{longdiv}{3.\strut^30\strut^60\strut^40}}\)
\( \frac {3}{8} = 0.375\)
Extra zeros are placed at the end until the decimal answer stops. This is called a finite decimal.
Converting fractions to percentages
Some fractions you will know as percentages.
\( \frac 12 \) =50\%, \( \frac 34 \)=75%
If it’s not one you know, then divide the numerator by the denominator and then multiply by 100.
\( \frac 38 = 0.375\)
\( 0.375 \times 100\) = 37.5%
Converting fractions to recurring decimals
A recurring decimal exists when decimal numbers repeat forever.
\( \frac 13 = 0.3333333333…\) the decimal never ends.
Dot notation is used with recurring decimals.
0.33333… is written as \(0.\dot{3}\)
The dot above the 3 shows that the 3 keeps repeating.
0.255255255… can be written as \(0.\dot{2}5\dot{5}\)
The dot above the 2 and the 5 shows that the numbers between the dots, 255 keep repeating.
Example
Change \(\frac13\) to a decimal.
Solution
\(\frac13 = 1\div3\)
(ܾԳDz3DZٵ0.3333…}ԳDzDzԲ徱1.ٰٰܳ10ٰٰܳ10ٰٰܳ10ٰٰܳ10…\)
\(\frac13 = 0.333333…\) the decimal never ends.
Using dot notation…
- 0.3333… is written as \(0.\dot{3}\)
Question
Change \(\frac56\) to a decimal.
Solution:
\(\frac56 = 5\div6\)
(ܾԳDz6DZٵ0.8333…}ԳDzDzԲ徱5.ٰٰܳ50ٰٰܳ20ٰٰܳ20ٰٰܳ20…\)
\(\frac56 = 0.833333…\) the decimal never ends.
Using dot notation…
- 0.833333… is written as \(0.8\dot{3}\)
This is to show that there is one 8 and then an infinite number of 3s.
Test yourself
More on M3: Number
Find out more by working through a topic
- count3 of 4
- count4 of 4
- count1 of 4