Interest only payments

in excel;

This simple example shows the interest payment for a $100,000 investment that earns 6% annually for 1 year. The interest payment is calculated for the 1st month and payments are due at the end of each month.

=IPmt(6%/12, 1, 1*12, 100000)


http://www.techonthenet.com/excel/formulas/ipmt.php
http://office.microsoft.com/en-us/excel-help/ipmt-HP005209145.aspx

this can also be simply calculated as: 100000*.06/12