Smooth a chart line without dummy data

I have inherited a spreadsheet and given the task of trying to get a line on a chart to show a smooth progression between actual values. Presently the user inserted dummy data in blank cells, to give the impression of a smooth line.

For example M2 contains £219,000. M5 contains £387,000. M3 and M4 are blank, but they have inserted the following formula to give "dummy" data which well then show a smooth line when charted:

M3 (which shows £275,000):

=((M5-M2)/3)+M2

M4 (which shows £331,000):

=((M5-M2)/3)+M3

There must be a better way of doing it than this?

Thanks!

Also posted here: https://www.mrexcel.com/forum/…mmy-data.html#post4744080

Re: Smooth a chart line without dummy data

Problem solved on the Mr Excel thread:

"Since that's a straight line, you can simply get the chart to plot that. Right-click it, choose Select Data, then click the Hidden and Empty Cells button, and choose the 'connect data points with line' option."