Convert decimal to Roman numerals
255 in decimal
CCLV
How it gets there
- Take the largest symbol that fits, repeatedly
- C = 100 C = 100 L = 50 V = 5
- Subtractive pairs
- IV, IX, XL, XC, CD and CM are the six pairs where a smaller symbol before a larger one means subtract. Only these six; IIX and VC are not numerals.
Why the working is here
Every other converter of this kind prints the answer and stops. A base is a positional system, so the answer is a sum you can check: each digit is multiplied by the base raised to its position, and the results are added. Going the other way is repeated division, reading the remainders upwards. Neither is a black box, and this page refuses to be one.