Reading Roman numerals, step by step

Roman numerals are the numbers on clock faces, book chapters and old building dates.

The question

XLVII

pieces:XLVII
pieces:XLVII
pieces:XLVII
XLreplacedXXXX
pieces:XLVII
values:40511
XLVII=47
  1. Split it into pieces before adding anything — most letters stand alone, but some come in twos.
  2. XL is a pair, not two letters each. A SMALLER letter in front of a bigger one is taken away: XL is 40 — not 60.
  3. That is also why four of the same letter never runs in a row. XL is what XXXX was replaced by — the pair exists so the fourth one never has to be written.
  4. Add the pieces up: 40 + 5 + 1 + 1 = 47.

How it works.

  1. 01

    Split it into pieces before adding anything — most letters stand alone, but some come in twos.

  2. 02

    XL is a pair, not two letters each. A SMALLER letter in front of a bigger one is taken away: XL is 40 — not 60.

  3. 03

    That is also why four of the same letter never runs in a row. XL is what XXXX was replaced by — the pair exists so the fourth one never has to be written.

  4. 04

    Add the pieces up: 40 + 5 + 1 + 1 = 47.