Geez. Everybody wants to give you a fish. I’d like to teach you to fish.
In the 70s, a program called Visicalc put PCs on every manager’s desk because it let you “play” with numbers. Change a number and see what happens. Today, you use Microsoft Excel for that same thing, though Apple Numbers or Google Sheets will do the same thing.
Excel etc. is a grid of spaces (cells) you put mostly numbers. However, you can also put in formulas, that compute results based on numbers in other cells.
This means if you change one value, boom, the entire spreadsheet recalculates based on that new value, and you can see the knock-on effects of that change. This is what the “What-if” game is all about. *It’s beyond the scope of this answer to teach you Excel, but I’ll hit the highlights. Rest assured you can easily learn what I’m showing you.
So we start out with a sheet that looks like
I did this from a blank sheet. I’ve done this a few times before, so I have a sense of how to do this. Notice how I put the final total on the right. You could put it on the left. Feel free to play and experiment - it’s what Excel is all about.
If you want to fire up a spreadsheet and follow along, feel free.
I have hand-entered in your first known values: The total amount owed (principal), and the first payment you want to make. Now, let’s do an easy formula: “What we owe now”. That’s just the amount owed, minus, what we paid. Most spreadsheets let you click a cell to specify a cell - that’s how I did this; I didn’t type in D4 or whatever. (But that’s allowed too). See me entering the formula here:
“OMG OMG it just calculated a number” — seriously though, this one thing is why managers in 1979 were willing to be seen with an Atari 800 computer in their office. Other managers would scoff and say “Playing Star Raiders?” And they’d grin and say “Come in here...”
The next step is to figure the interest for 1 month. We only pay interest on the money we didn’t pay down, so we need to compute it based on that number we just resolved in the above formula. So let’s enter the formula that will derive 1 month’s interest (remembering the 1.69% is an annual rate, so we must divide by 12).
Notice how the earlier formula is now hidden, and it simply shows the result. That will happen here too.
Next, to figure out what we owe now, we add the interest. A simple addition:
Now presumably in the next month, we want to make hte same payment as last month, so I just do that as a (rather simple) formula too.
I don’t want to belabor using Excel, but look for a “Fill down...” function that will let you replicate those formulas in the rows below. I would only bother to do 4 months because that is more than enough to give you your answer.
Now, the spreadsheet has unlimited width, so in the columns to the right of here, do exactly the same thing with the smaller loan. Changing 0.0169 to whatever that loan’s interest rate is.
Notice that almost all the cells are formulas. In fact there are only 2 things that you would change: the payment amount in the first row for each loan.
I would add one more formula near the top that picks up the “owed” amount after 4 months on each loan and adds them. That way you can see your total debt amount in one cell. Now as you change the 2 payment values, you can watch the debt amount change.