Most people are used to a spreadsheet approach when it comes to interest related calculations. Such an approach has a line (row) for each year and or month. To fill out the table we use controllers and a button. contains a simpler approach with a few variables and results in the same row. The spreadsheet alike approach
The multiplier is not needed as separate column, but the number show (certainly when you test with a round number for amount like 1000 Euro) is a number that you see back in the last column.
The part below shows a bit how a spreadsheet approach in Coda makes it unnecessary difficult (in my opinion).