Detect changes to array elements value in inspector

Hi Guys, simple question. I have a list (or it could also be an array) in my inspector.

public List<float> intList;

or

public float[] floatArray;

I can have as many elements in each list or array as I like, but the constraint is that the numeric sum of all element values in the array must always be 10.0

So lets say if my list (or array) had 3 elements, each with the values:

[0] = 3.0 
[1] = 5.0 
[3] = 2.0

If i adjust element [3] to have a value of 10.0, I need to do some calculation and reduce both [0] and [1] to value of 0.0… because the sum of all elements must always be equals to 10.0 ! (Sum of element values, not count of elements!!!)

The problem is not the calculation, but how do i detect that an element value was changed in order to run some custom code to repopulate the values in other elements?

Thanks
Kevin

Unity has an OnValidate() function to hook for this purpose Unity - Scripting API: MonoBehaviour.OnValidate()