Enter either an Arabic or a Roman numeral and it will be converted into the other. Roman numerals cannot be negative and there is no roman numeral zero. The calculator accepts non-standard roman numerals such as IM and IIII, but such numerals are normalized to their canonical form.
Lowercase letters are used to represent large numbers. This is not standard practice. Often a bar is placed above a Roman digit to indicate that is 1000 times larger than normal. Since letters with bars are not standard characters and computers cannot easily handle them, lowercase is used instead.
The self test does not accept non-standard roman numerals and each correct answer makes it more challenging.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
Copyright Stephen Ostermiller 2001-2014