Capture a field old value and a new value in a form?

Dear All,

Lets say I have a field call number (int) and its = 5

now the user change it and enterd 6.

How can I capture the field old value and new value? I want to say that Field old value = 5 and new Value = 6.



Xrec.Field contains 5 and Rec.Field contains 6

If you want to use it in future also then you have to save the old value in a another field

Thanks alot