Libre calc problem

I have inserted a graph, I have the table with all the data needed and have made the graph from it. The problem here is that most of the data is ‘averages’ some of which have several decimal points. Most of these can be reduced to 2 decimal points, except one in particular. It has about 5 decimal places and when I try to reduce the amount of places the cell goes immediately to ### this is peculiar to only this one cell, all the others just work as expected. Can someone out there explain what I am doing wrong in this cell.?
Thanks for your consideration in this matter.
Rod.

What do you see in the cell with ### if you make it wider?