Have you long forgotten how to decipher those Roman numerals you learned in elementary school or Latin class or were you absent when the rest of the kids learned them and never quite got the hang of deciphering those pesky Is, Vs, and Xs?  As a bookseller, I am constantly coming across Roman numeral copyright dates, so here's a brief explanation, especially designed for those of you trying to do book date conversions.  

Here are the basic numerals 1-11:

I: 1; II: 2; III: 3; IV: 4 (1 minus 5); V: 5; VI: 6 (5 plus 1): VII: 7; VIII: 8; IX: 9 (1 minus 10); X: 10; XI: 11 (10 plus 1).

As you can see, with IV and IX, you take away 1 from the number that follows (5 and 10) to get 4 and 9. Conversely, with VI and XI, you add 1 to the number that precedes (again, 5 and 10) to get 6 and 11.

Once you've mastered 1-11, you can start deciphering larger numbers. Here are some examples, and a quick check to see if you've got it!

XIII:13; XIV:14; XXV: 25; XXXIV: 34; XXXVI: 36; XXXIX: 39

Check your progress: XIX, XXXIII, XXVIII, XXXVII

Answers: 19, 33, 28, 37

Let's move on. Roman numerals are easy once you get the hang of them, but. there are a few quirks. 40 is not XXXX,  50 is not XXXXX, and 100 is not XXXXXXXXXX. The Romans liked to use as few characters as possible to make the numerals easier to read. So, L:50, C: 100, D: 500, and M: 1000. That means the following:

Just like 4 is IV (1 minus 5), 40 is XL (10 minus 50), and just like 6 is VI (5 plus 1), 60 is  LX (50 plus 10);

Your turn: What would 70, 80, 90, 110, and 2000 be?

Answers: LXX (50 plus 20); LXXX (50 plus 30); XC (10 minus 100) ; CX (100 plus 10); MM (1000 plus 1000).

Okay, now let's put it all together to get some copyright dates. Let's try 1965. If you remember that MCM is 1900 (1000 plus 100 minus 1000=900), then you just have to concern yourself with the numbers that come after 1900, which in this case would be 65.  60 is 50 plus 10=LX and 5 is V. Put it all together and you get MCMLXV. 2004 would be MMIV (1000 plus 1000 plus 1 minus 5. Usually, it's best to group the numbers to make them easier to deciper. Above, the grouping would be MCM  LX  V for 1900, 60, 5.

What years are these?

1. MCMXXVII (MCM  XX  VII)

2. MCMXLIX

3. MMVI

4. MDCCCLXII

5 MCMLIV

Answers: 1927, 1949, 2006, 1862, 1954

Give yourself an A+ and have fun with Roman numerals. They are great mini-brain exercises.