FRACTIONS, DECIMALS & PERCENTAGES
FRACTION OF A QUANTITY
We find a fraction of a number by dividing the number by the
denominator and multiplying the answer by the numerator.
PERCENTAGE OF A QUANTITY
A percentage is a fraction out of 100. i.e. 50% = .
A lot of common percentages can be written as simplified fractions.
To find a percentage of a quantity we can use the fractions above.
e.g 10% of £58 =
of £58 = 58 ÷ 10 = £5.80
To find 5% of £58 we first find 10% of £58 then half the answer.
To find 40% of £600 we first find 10% of £600 then multiply the answer by 4.
PERCENTAGE OF A QUANTITY ON A CALCULATOR
To calculate a percentage on a calculator we divide the number
by 100 and multiply by the percentage.
e.g. 62% of 28500 = 28500 ÷ 100 x 62 = 17670
CONVERTING BETWEEN FRACTION, DECIMAL & PERCENTAGE
FRACTION
DECIMAL
DECIMALS – Divide numerator by denominator e.g.
FRACTION – The first decimal place is tenths so
The second decimal place is hundredths so
etc
DECIMAL
PERCENT – Multiply the decimal by 100 e.g. 0.8 = (0.8 × 100)% = 80%
PERCENT
DECIMAL – Divide by 100 e.g. 35% = 35 ÷ 100 = 0.35
FRACTION
PERCENT
PERCENT - Divide numerator by denominator and multiply by 100
e.g.
FRACTION – Divide by 100 and simplify e.g.
EXPRESSING QUANTITIES AS PERCENTAGES
We are often required to change values into percentages.
e.g. In a test Karen scored 18 out of 24, write this as a percentage.
18 out of 24 is a fraction so follow the rule above i.e. divide and multiply by 100.
Fractions, Decimals & Percentages Practice
http://www.bbc.co.uk/bitesize/standard/maths_i/numbers/percentages/revision/1/
Learn about percentages and try the testbite.
http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i17/bk7_17i1.htm
http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i17/bk7_17i2.htm
http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i17/bk7_17i3.htm
http://www.cimt.plymouth.ac.uk/projects/mepres/book7/bk7i17/bk7_17i4.htm
Learn about fractions, decimals and percentages and answer the questions.
http://www.mathplayground.com/balloon_invaders_percent.html
Percentages game.
www.supermathsworld.com Ask your teacher for login details.
Select Number from the options.
Select DECIMALS from the menu. Try the Easy, Medium and Hard levels.
Select FRACTIONS 2 from the menu. Try the Easy level.
Select PERCENTAGE 1 from the menu. Try the Easy, Medium and Hard levels.