Hi arshan, and thanks Chris,
I haven't done it but if you enter your sales figures and you month number into the regression part of any normal sci calc you should get a=311.77 and b=4.94
\(expected\; \\ Y = a+bx\\ Y=311.77+4.97x\)
a is the y intercept. = expected sales at start
b is the gradient, since this is a linear (straight line) regression it means that every month the sales are expected to increase by 4.97 units
The Ft is the expected sales (using the regression line) for any given month.
https://www.desmos.com/calculator/6mudoucnoy
Does that help ??