Remember Price Elasticity of Demand Formula measures how much quantity demanded responds to a change in price. Elastic: Large responses (elasticity coefficient > 1) Inelastic: Small responses (elasticity coefficient<1) Price Elasticity of demand = Percent Change in Quantity Demanded Percent Change in Price 7. Calculate as you use the formula above Price of gasoline rises by 10 percent, quantity demanded fal by 25 percent. What is the price elasticity of the demand number and is it elastic or inelastic