Finding the percentage change
The formula: percentage change = change / original X 100
Put into practise: A trader buys watches for £5 and sells them for £7. Find his profit as a percentage.
percentage profit = 2/5 X 100 = 40%
Finding the original value
1) Write the amount in the question as a percentage of the original value.
2) Divide to find 1% of the original value.
3) Multiply by 100 to give the original value. (=100%).
Put into practice: A house increases in value by 20% to £72,000 find what it was worth before the rise.
1) An increase of 20% means £72,000 represents 120% of the original value .
2) Divide by 120 to find 1% of the original value
3) Then multiply by 100.
X100 £60,000 = 100%
So the original value was £60,000
Simple interest means that a certain percentage of the original amount only is paid at a regular intervals (usually once a year). So the amount of interest is the same very time it's paid.
Put into practise: Regina invests £380 in an account which pays 3% simple interest per annum. How much interest will she earn in 4 years?
1) Work out the amount of interest earned in one year
380/100 X 3= £11.40
2) Multiply by 4 to get the total interest for 4 years.
4 X £11.40 = £45.60