Why is it that Maths students, even those doing Further Maths, can never calculate a %? Every year I realise that very few students know how to calculate a %. Maybe it is not on the A Level maths syllabus?

% are one of the few maths learning of great practical use. When shopping, you won't have to differentiate a complex equation, but, you may need to work out the 20% discount of a good costing £40.

Anyway rant aside.

How to calculate a Percentage %

• 20% of £40

• 20% means 20/100. Therefore we multiply £40 * 20/100 = £8

20% 20/100 is the same as 0.2

• If price increases from £40 to £44. What is the % increase?
• We divide the difference (44-40) by the initial amount. * 100
• Therefore it is 4 / 40 = 0.1
• 0.1 * 100 = 10%

• If price increases from 70 to 84. The % change is 14/70 *100 = 20%

If quantity was 3,000 and the Q.D increases by 20%. What is the new quantity?

we can times 3,000 * 120/100 = 3,600

Alternatively we can find 20% of 3,000 and then add it to 3,000

20% of 3,000 = 20/100 (0.2) * 3000 = 600

• Price Elasticity of Demand

Labels: maths