format a cell to warn you if the number don't add up.

[Roha1]

I need a way to make a warning if the cell value don't add up with another number.

example.
15 rolls don't add up in a box of 10. Then it should pop-up a warning and let you choose between 10, 20 or to don't do anything.

Hope there is an easy way of doing it.
Thanks for any reply

 

[Joe4]

I think we need more detail:

1. How are the values currently being entered?
2. What cells are they being entered into?
3. What is the rule for what they should add up to?