Documents written before the seventeenth century may have numbers in them which are expressed as Roman numerals. These are written from left to right, starting with the largest number and ending with the smallest (with one exception). To convert them into decimal you need to add all the numerals up. You can use the chart below to help you.
In medieval documents numbers are usually distinguished from words by having a dot placed before and after them.
The Exception
Sometimes you will see a smaller numeral placed before a larger numeral, for example CM. When this happens you subtract the smaller from the larger, for example CM represents 900 and IV represents 4.
| Decimal | Numeral |
|---|---|
| 1 | i, j or I |
| 2 | ii, ij or II |
| 3 | iii, iij or III |
| 4 | iiii, iiij, IIII, iv or IV |
| 5 | v or V |
| 6 | vi, vj or VI |
| 7 | vii, vij or VII |
| 8 | viii, viij or VIII |
| 9 | ix or IX |
| 10 | x or X |
| 20 | xx or XX |
| 30 | xxx or XXX |
| 40 | xl or XL |
| 50 | l or L |
| 100 | c or C |
| 500 | d or D |
| 1000 | m or M |
Examples
- MCMLXXVIII – This is the year 1978 (1000 + 900 + 50 + 10 + 10 + 5 + 1 + 1 + 1)
- MMX – This is the year 2010 (1000 + 1000 + 10)
Sometimes J is used instead of an I to signify the final unit, perhaps to stop tampering with the document after it had been written.
- MDCXXXIJ – This is the year 1632 (1000 + 500 + 100 + 10 + 10 + 10 + 1 + 1)
Roman Numerals & Counting in Scores
Historically in Britain we used to count in scores, which means to count in units of twenty. So four score and twenty is the same as 100. We adapted Roman numerals slightly to incorporate this system, something you may come across when conducting family history research.
When you see numerals written above other numerals it means multiply the two sets, so for example iiij with two x’s above would equal 80 (four units multiplied by twenty).
Sometimes the numeral to multiply by may be in superscript, for example vjc equals 600 (6 multiplied by 100).