Page 103 - Knowledge Organiser Yr8 24-25

Knowledge Base: Mathematics TOPIC 22: Percentage Change Year 8 | Summer Term 1
By the end of this topic you should be able to:-
• Change between fractions, decimals and percent
• Find percentage of amounts
• Find percentage increase
• Find percentage decrease
• Use a multiplier and calculator to find percentage increase and decrease
Percentage
A number which means ‘out of’ 100
85% means 85/100
Language
Meaning
Example
Percentage Increase / Decrease
Changes expressed as fractions out of 100
35% = 35/100 = 0.35
Percentage Change
The percentage increase or decrease that changes an original amount to a new amount
A car that cost £25,000 is now worth £15,000. This is a percentage reduction of 25%
Equivalent decimal
The decimal number that equals a given percentage
The decimal equivalent of 17.5% is 0.175
Decimal Multiplier
The number you multiply by to calculate a percentage change
To increase by 25% you multiply by 1.25 To decrease by 25% you multiply by 0.75
Important things to remember:-
1) Ratio compares the size of the parts
2) Proportion compares the size of a part with the whole
Worked examples
103