These programs enable easily and accurately calculating TVM and amortization problems on old Casio calculators in about 350 bytes of code.

## Casio fx-6300g Comparison Bug

The Casio fx-6300g graphing calculator has a subtle bug that affects using certain comparison operators against array memories, which will effectively cause the two sides of the comparison operator to be swapped. Here's how to trigger the bug, and what you can do to avoid it.

## Median-Median Regression For TI-86

Despite being released about 4 years after the TI-82, the TI-86 does not include median-median regression, which can be a useful method of linear regression for data with extreme outliers. Fortunately it's a simple enough algorithm to implement in a small program.

## chmod Calculator For TI-86

Here's a small TI-86 program for twiddling Linux/UNIX permission bits and seeing both the symbolic and numeric results. The simple ones (750, 640, 755, etc.) are easy enough to do in one's head, but it can start to get a bit messy when setuid, setgid, and sticky get involved.

## Some Programs For the Casio fx-6300g

I bought an old Casio fx-6300g graphing calculator from ebay (it's so tiny!), and couldn't find many programs written for it. Who would imagine that the internet wouldn't be awash in programs for an obscure, low-end calculator from 27 years ago? So, I wrote a few: prime factors, binomial probability, and negative binomial probability.

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