I've set up a spreadsheet to enter the current time and date in particular
cells when data is entered into another cell (basically i'm using a formula
to record the time data was entered into each cell).

I've used the following formula to do so, =IF(C20,NOW( )),
Problem is the cell just updates when the file is saved as the formula gets
recalculated.

I believe i need to find a way of allowing induvidual cells to calculate
only once to prevent this from happening.

Anyone have any ideas? or know of another way to accomplish this task?