# How do you find the slope of a demand curve?

The slope of a demand curve can be found just like the slope of any other line. Remember, in order to find a slope, you must divide rise by run. In the case of a demand curve, this means dividing change in price by change in quantity demanded. Mathematically, this looks like $\left({P}_{\text{2"-P_"1")/(Q_"2"-Q_"1}}\right)$
Note that in order to calculate this slope, you need two points that you know are on the demand curve. The ordered pairs of course being $\left({Q}_{\text{1",P_"1") and (Q_"2}} , {P}_{2}\right)$. Remember that this works ONLY when the demand curve is linear. If you are taking a calculus based economics course, the slope is the derivative at the specific quantity value. If you have not learned learned derivatives yet, I will extend my answer.