Here is my situation. I am trying to make a spreadsheet in microsoft excel. i want to be able to input a number in A7 and have it automatically change A6 That i know how to do. but then i want to be able to put a different number in A7 and have it change A6 using it's previous value. for example. A6 = 12. I enter 5 in A7. A6 now = 17. i want to be able to delete 5, enter 6 and now have A6 = 23. i personally don't think it is possible and i have researched to no avail. however any help is appreciated. i am fairly expirienced with excel so don't be afraid to use terminology. if this is not possible suggestions for other programs to use will help also. thanks again.