Price elasticity of demand?

Question

if the price of product increases from £5 to £6 & quantity demanded falls from 500 to 450 a month , PED = 10/20 = 0.5. Can somebody explain how to arrive at this figure I don't understand how to do it.

Answer 1

PED = (% Change in Quantity Demanded)/(% Change in Price)
% change in quantity demanded = (500 - 450)/500 = 10%

% change in price = (5 - 6)/5 = 20%

So PED = 10/20 = 0.5

The article attached is a simple one to follow.