How to Learn Roman Numerals
To learn Roman numerals, know that I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1,000. If a symbol comes after another symbol, then you add it to the symbol before it. For example, VI = 6 since V = 5 and I = 1. If a symbol comes before another symbol, subtract it instead. For example, IV = 4. Also, keep in mind that you can't have more than 3 of the same symbol in a row. So, instead of writing VIIII for 9, you'd write IX.
Understand the basic symbols. Here's what you need to know to get started: I = 1 V = 5 X = 10 L = 50 C = 100 D = 500 M = 1000 Use a mnemonic to memorize the value order of the symbols. If you have a hard time remembering what goes where, just try this simple one: M y D ear C at L oves X tra V itamins I ntensely. Learn all of the digits in the ones place. Here they are: I = 1 II = 2 III = 3 IV = 4 V = 5 VI = 6 VII = 7 VIII = 8 IX = 9 Learn all of the digits in the tens place. Here they are: X = 10 XX = 20 XXX = 30 XL = 40 L = 50 LX = 60 LXX = 70 LXXX = 80 XC = 90 Learn all of the digits in the hundreds place. Here they are: C = 100 CC = 200 CCC = 300 CD = 400 D = 500 DC = 600 DCC = 700 DCCC = 800 CM = 900 Know that you can't have more than three of the same symbol in a row. When you place the same symbols together, you can just add their values. Normally the maximum number of the consecutive same symbols is three. II = 2 XXX = 30 Add smaller symbol values that are placed after large symbol values. Similar to the above rule, just add their values together. Remember the numeral must have the larger symbol value first for this to work. Here's how you do it: XI = 11 MCL = 1150 Subtract smaller symbol values that are placed before larger symbol values. In this case, you need to subtract the smaller value from the larger value. Here's how you do it: IV = 4 CM = 900 Know how compound numbers are written. There are numerous rules that govern the way Roman numerals are supposed to look. Here are some rules to know: IV should be used rather than IIII 2987 is written as MMCMLXXXVII because: The first M gives you 1000 The next M gives you 1000 The next CM gives you 900 The next LXXX gives you 80 The next VII gives you 7 Therefore if you add the amounts together, you will get 2987. Learn to write larger numbers. Since M = 1,000, if you want to represent one million, a bar, or line, is added above the numeral M, equaling one million. The bar above the numeral represents that figure times one thousand. Thus, M x M= 1,000,000. Five million would be represented by MMMMM with a bar above each M. This procedure is necessary because in Roman numerals, there is no larger symbol than M (1,000). This method isn't commonly used, but it's good to know how it works. Check your work. If you want to make sure you converted a number correctly, check out some online converters to see if you're on track. 
Understand the basic symbols. Use a mnemonic to memorize the value order of the symbols. Learn all of the digits in the ones place. Learn all of the digits in the tens place. Learn all of the digits in the hundreds place. Know that you can't have more than three of the same symbol in a row. Add smaller symbol values that are placed after large symbol values. Subtract smaller symbol values that are placed before larger symbol values. Know how compound numbers are written. Learn to write larger numbers. Check your work. 