Here is an example of how to calculate a percentage increase/decrease in an OpenOffice spreadsheet (calc).
In the cell window enter “=(C5-B5)/B5” and hit enter. The result window (D5) will display the percentage increase from old number (B5) to new number (C5).
In this case 752-565/565= 33.10%
The formula is, the new number minus the old number divided by the old number.
Keep in my mind the result cell (D5 in this example) must be formatted for percentage. To do this, select the cell, right mouse click, select format cell, select percentage.
I got tired of Googling this every time. There’s probably an easier way to do it, but this one works for me.