Rather that explain the problem. Its probably better to see it below. Having problems using the percentage difference column to compare a value between two tables.

In summary, I only want 3 columns in the below and not to show column 2.

And also if there is a null value, can it return zero so the percentage across works?

Code here - (ZN(SUM([Number of Records])) - LOOKUP(ZN(SUM([Number of Records])), -1)) / ABS(LOOKUP(ZN(SUM([Number of Records])), -1))

Thank you!