Spreadsheets also have financial functions built in. Here is how to compute the answer to example 2 using Excel:
(1) Click on the cell where you want the answer displayed.
(2) In the "Insert" menu, choose "Function." (or click the function icon in your toolbar, [fx])
(3) Choose the "financial" function category, and choose "RATE" and a box pops up.
(4) Now fill in the spaces in the box: Nper = 60, Pmt = -300, Pv = 15000, Fv = 0, and ignore type
(5) The formula result displays at the bottom of the box, "Formula result = .6183413161%." This is i/12, so multiply by 12 to get the annual yield to maturity of 7.42%