I have a spreadsheet that keeps track of the amount of loan payment someone should pay every month. I would like to "lock" this value, once this calculation has been made. For example:

In january I borrow $ 100 and want to pay it back in 10 months...making monthly payments $10
However in march I borrow an additional $50 and still have to pay the rest of the $100 ($80) + $50 in 8 months...(So I can borrow money for a period of 10 months, but if I borrow more money I still have to be debt free by the end of those initial 10 months), I would like to "freeze" the values of Jan and february to 10 eventhough my amount has changed to 150.

My goal is to simply freeze the cell value once the formula has calculated it.

Hope someone can help,

TechSteff