## Approximating Duration, Modified Duration, and Convexity with Option Free Bonds

The use of Excel’s PRICE function can eliminate much of the math required to understand how modified duration and convexity can be used to predict the price change in option-free bonds. The spreadsheet for this post is called “Option Free” and like all of my spreadsheets, it can be downloaded for free. The sheet is […]

## 30/360 Present and Future Values with Dates

In my very first post back in August of last year titled “No XNFV Excel Function?” I showed formulas for calculating present value and future values when cash flows with dates are given. These formula were calculated based upon actual days between dates and a 365 day base year. I lamented that Excel has a function that calculates present values with dates […]

## Amortization Consolidation

If you have looked at very many of my posts and spreadsheets, it is obvious that a good deal of them involve loan amortization schedules. So does this one. The first sheet in the workbook “consolidate” is called “Amortization Loan”. That is because it contains a standard monthly amortizing loan schedule. There are times when […]

## Solve for a target net worth ratio

Math majors can skip this one. I found it looking through my files and thought it might be useful to some credit union financial managers. The math problem is: How much of a change in capital would it take to move the net worth ratio from the current level, to another level. At first glance it seems […]

## Simple Interest

Both Child Support #1 and #2 have been simplified in order to correct a problem which includes the prepayment of support. This results in the payer earning the stated interest rate on the positive balance prepaid, which is typically much higher than market rates, and may not be allowed in some jurisdictions. Although there are […]