convert 'calculation result' to actual 'number'

Hi,
I have a need to convert a 'calculation result' into an actual 'number' so I can operate on the resulting data.

For example: if the 'average(a1:a20)' = 4.2; I'd like to just have the '4.2' without the formula behind it in the cell or a resulting cell.

thank you,

chubs