How to Read Roman Numerals

Step-by-Step Guide

1. 1

   Step 1: Learn the basic value of each digit.

   There are only a few Roman numerals, so it doesn't take long to learn them:
   I = 1 V = 5 X = 10 L = 50 C = 100 D = 500 M = 1000
2. 2

   Step 2: Use a mnemonic.

   A mnemonic is a phrase that you can memorize more easily than a list of numbers, that will help you remember the order of the digits.
   
   Try repeating this one to yourself ten times:
   I Value Xylophones Like Cows Do Milk., If the digits are ordered largest to smallest, all you need to do to read them is add the value of each digit.
   
   Here are some examples:
   VI = 5 + 1 = 6 LXI = 50 + 10 + 1 = 61 III = 1 + 1 + 1 = 3 , Most people who use Roman numerals save space by using subtraction to show certain numbers.
   
   You'll know this is happening if a smaller digit is in front of a larger digit.
   
   This only happens in a few situations:
   IV = 1 subtracted from 5 = 5
   - 1 = 4 IX = 1 subtracted from 10 = 10
   - 1 = 9 XL = 10 subtracted from 50 = 50
   - 10 = 40 XC = 10 subtracted from 100 = 100
   - 10 = 90 CM = 100 subtracted from 1000 = 1000
   - 100 = 900 , If you need to, divide a number into groups of digits to understand it better.
   
   Always make sure you catch any "subtraction problems" with a smaller digit in front of a larger, and include both the digits into the same group.
   
   For example, try to read DCCXCIX.
   
   There are two places in the number with a small digit in front of a larger one:
   XC and IX.
   
   Keep the "subtraction problems" together and break up the other digits separately:
   D + C + C + XC + IX.
   
   Translate into ordinary numerals using the subtraction rules when necessary: 500 + 100 + 100 + 90 + 9 Add them all together:
   DCCXCIX =
   799. , If a horizontal line is drawn across the top of a number, multiply the value by 1,000.Be careful, though: many people draw a horizontal line above and below every roman numeral, just as decoration.
   
   For example, an X with a "–" written over it means 10,000.
   
   If you're not sure whether the bar is just decoration, think about the context.
   
   Would a general send in 10 soldiers, or 10,000? Would a recipe use 5 apples, or 5,000?
3. 3

   Step 3: Add numbers with larger digits first.

4. 4

   Step 4: Treat numbers with smaller digits first as subtraction.

5. 5

   Step 5: Break a number into parts to understand it.

6. 6

   Step 6: Look for a horizontal bar for very large numbers.

Detailed Guide

About the Author