I'm making a spreadsheet showing every mortgage payment I make split into:

Payment Taxes Insurance Interest
Principal Balance


Based on the fixed payment amount every month, the fixed Tax and
Insurance amounts every month and the difference in Balance from payment to
payment, calculating what percent of the payment and the dollar amount that
went to interest and what percent of the payment and the dollar amount that
went to pricipal is pretty remedial - but I can't find the function to insert
under Interest and Principal to calculate it. Somebody please help??