I have found a reference which has some rules for constructing roman numerals. Firstly, four of a given numeral is okay, but five or more is not. This allows VIIII to be valid. You must use the largest numeral at a given stage, so for 15, you don't write VVV, you write XV. Numerals of a lower value, when written in front of a higher valued numeral subtract their value from the higher valued numeral. Further rules for the subtraction: o Only I X and C can be used in this way. V, L and D cannot (nor can M) o Only one smaller numeral can be written first. So XIIX is not valid for 18. o The lower numeral must be no less than a tenth of the value of the higher numeral. o It specifically states that each power of ten is handled separately, and uses the example that 49 is NOT IL, it is correctly XLIX. These are the rules I have used in my routine... Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+