Hello!

I have four cells in a column (c1, c2, c3, c4). The sum of these cells should equal one for True. Users will be adding weight values (i.e, .05,.25, etc).
The sum of the values should be 1 not over.
Trying to use data validation so I can display an error when the weight values need to be adjusted.
In data validation, I use the customer option so I can enter a formula. I have tried IF and OR functions, but without luck.
Logic steps:
If weight value in c1 >= 1
Or
If weight value in c1+c2 >= 1
Or
If weight value in Sum(c1:c3) >=1
OR
If weight value in Sum(c1:c4) >=1

Display error message for user to adjust their weight values.
Simple enough. Trying to do this in Data Validation because I want the error msg to display when the value the user enters puts the total over 1, so I'm attempting to cover each new cell value with previous cell values.
Can I do this data validation or does this require VBA?

Many thanks!