Percentage, fraction and decimal, three spellings of one number is in the Primary 5 Percentage chapter. The lesson film below teaches it with its own questions, and the practice set is written for Primary 5.
Lesson video, with the working
One number, three ways to write it
2 min 46 s
The film teaches 2 questions in turn. Each question shows first; its working is written as the film explains it.
How do you solve P5 fractions, decimals and percentages questions?
A fraction, a decimal and a percentage can name the same amount, and Primary 5 questions ask your child to change one into another.
What your child learns here
A fraction, a decimal and a percentage can name the same amount, and Primary 5 questions ask your child to change one into another. This page uses hundredths as the bridge: 65% is 65/100, which is 0.65, and 0.4 is 40/100, which is 40%.
Percent means hundredths, so any percentage can be written over 100 straight away.
Dividing by 100 moves each digit two places to the right, so 65 ÷ 100 = 0.65.
A decimal with tenths only is rewritten in hundredths first: 0.4 = 40/100 = 40%.
A fraction becomes a percentage by making its denominator 100, as in 3/20 = 15/100 = 15%, or by multiplying it by 100%.
A percentage written as a fraction is simplified at the end: 45% = 45/100 = 9/20.
Answers such as 125% and 62.5% are normal when the amount is more than one whole or includes eighths.
Does the answer make sense?
Change the answer back the other way. 35% is 35/100, and dividing 35 and 100 by 5 gives 7/20, the fraction Question 1 started with.
Size tells you a lot as well. Half of 20 is 10, so 7/20 is less than a half and its percentage has to be under 50%, while 5/4 is more than one whole and must come out above 100%.
How to practise these questions
Free Question 1 asks your child to express 7/20 as a percentage by turning twentieths into hundredths. Basic questions train every direction of change: a percentage to a decimal and to a fraction in simplest form, tenths and hundredths to percentages, eighths that need a half in the percentage, and an improper fraction that comes out above 100%. Challenge questions turn a mixed number into a percentage, or put a fraction, a decimal and a percentage in order from the smallest. If one form will not match another, open its worked solution and try the question again later from Revision.
Questions parents ask
How do you change a percentage to a decimal? Write it over 100, then divide by 100. 65% is 65/100, and 65 ÷ 100 = 0.65.
Why is 0.4 equal to 40% and not 4%? 0.4 is 4 tenths, which is 40 hundredths. Percent counts hundredths, so 0.4 is 40%, while 4% would be 0.04.
Does my child need to change between all three forms? Yes. The use of % and expressing fractions as decimals are both Primary 5 outcomes, so questions move between fractions, decimals and percentages in either direction.
