In this video I will teach you a trick that you can use to find the gradient and equation of a line using a CASIO FX991EX calculator. The trick works by using the statistics linear regression function to find the line of best fit using interpolation. This can be used to find the equation of a line passing through two points or the gradient given two points.

Note that this method finds the line of best fit. If the value of r is not 1 or 1 there is no line that goes through the two points and the calculator gives a line of best fit.

The same method can be used on a Casio FX570EX Classwiz.