A few years ago as part of a program to convert between bases I included a Roman to Base 10 and Base 10 to Roman feature for the TI-85. It should work on a TI-86 too. It is limited to numbers less than 4000. If anyone wants them I could send them a copy, documentation is meager to none. I tried to faithfully follow all the rules I learned for Roman Numerals. For 1999 it gives: MCMXCIX Gary Wardall