Calculating a difference on a diagonal

[Hettie2102]

I have a data set in the form of a triangle. Each column is a year, and each row is a month. The rows calculate the balance on a cumulative basis.  I need to be able to calculate the difference in the lead diagonal (therefore the balance on the diagonal, less the number on the row before it). Please see the document attached. . The orange 'number' needs to be subtracted from the red. But as the data set is on a diagonal I am unsure on how I can calculate this in alteryx. 

Any help would be greatly appreciated, thanks! 

[atcodedog05]

Hi @Hettie2102 

Interesting can you provide some sample data and excepted output

[PhilipMannering]

Interesting problem!

You could try something like this...

[Hettie2102]

Hi please see below:

Thanks 

[PhilipMannering · Accepted solution]

Ah, think I misunderstood your question.

Try this,

[Hettie2102]

Thank you so much!