I want to display, in a KPI widget, a simple forecast of the current month of sales. To get this forecasted number, I need to divide the current MTD sales by the number of business days elapsed in the current month, then multiply that by the total number of business days in the current month to get a very rough forecast of what the month-end total will be. I want this total number to be displayed in the widget.

So far I've created a couple of formula columns:

- Number of business days elapsed in the current month called "curr_bus_day"

  business_days(start_day(month,current_date()),current_date())

- Number of total business days in the current month called "total_bus_day"

  business_days(start_day(month,current_date()),end_day(month,current_date()))

And an aggregate formula to get the current MTD sales:

  mtd(sum("my_table"."line_item_total"),"my_table"."date")

But I'm not sure where to go from here and how to fit these pieces together. I tried to calculate it all in a new formula column but I can't use aggregate formulas in a formula column. I tried to calculate it in an aggregate formula with the following but this aggregate formula doesn't appear as an option in the "Data Column" dropdown in the widget editor for some reason:

  (mtd(sum("my_table"."line_item_total"),"my_table"."date")/first_value(sum("my_table"."curr_bus_day")))*first_value(sum("my_table"."total_bus_days"))

This is dividing the MTD sales by the first value of the curr_bus_day formula column which is the number of business days elapsed, multiplying that by the first value of the total_bus_days formula column. But this seems like the wrong way to do it.

Any suggestion or tips?