I am trying to calculate (commercial) mortgages where the interest it
calculated on actual/360 basis. This keeps the monthly payments the same as
the regular PMT function, but with actual/360 it 'charges' 5 extra days
interest, meaning you pay the same but within your mortgage payments you are
paying 5 extra days interest and therefore less principal.

The monthly payments are the same as regular, but the balance at the end of
the term (on baloon mortgages, for example 10-year term on a 30-eyar
amortization) is higher with actual/360.

Question is, I need an elegant way to calculate that balance at the end of
the actual/360 term.