How to convert Numbers to Roman Numerals
Unlike the international numbering system, the Roman Numeration System uses only 7 symbols to write any number.
They are I, V, X, L, C, D and M
I - 1
V - 5
X - 10
L - 50
C - 100
D - 500
M - 1000
Follow these rules to convert a number between Roman System and the International System.
Rule 1: Repetition of a Roman Numeral means addition
Example: III = 1 + 1 + 1 = 3,
XX = 10 + 10 = 20
Rule 2: If a smaller numeral is written to the right of a greater Roman numeral, then the smaller is always added to the greater one.
Example: VII = 5 + 1 + 1 = 7,
XV = 10 + 5 = 15,
XXVI = 10 + 10 + 5 + 1 = 26
Rule 3: If a smaller numeral is written to the left of a greater Roman numeral, then the smaller is always subtracted from the greater one.
Example: IV = 5 - 1 = 4,
IX = 10 - 1 = 9,
XIX = 10 + (10 - 1) = 19
Some points to remember
1. There is no zero in the Roman System.
2. There is no concept of place value in the Roman System.
3. No symbol will repeat continuosely more than three times in any number
Example: 9 is written as IX, not as VIIII, 40 is written as XL, not as XXXX
Rule 1: Repetition of a Roman Numeral means addition
Example: III = 1 + 1 + 1 = 3,
XX = 10 + 10 = 20
Rule 2: If a smaller numeral is written to the right of a greater Roman numeral, then the smaller is always added to the greater one.
Example: VII = 5 + 1 + 1 = 7,
XV = 10 + 5 = 15,
XXVI = 10 + 10 + 5 + 1 = 26
Rule 3: If a smaller numeral is written to the left of a greater Roman numeral, then the smaller is always subtracted from the greater one.
Example: IV = 5 - 1 = 4,
IX = 10 - 1 = 9,
XIX = 10 + (10 - 1) = 19
Some points to remember
1. There is no zero in the Roman System.
2. There is no concept of place value in the Roman System.
3. No symbol will repeat continuosely more than three times in any number
Example: 9 is written as IX, not as VIIII, 40 is written as XL, not as XXXX
Keeping all these points in mind, let's convert some numbers to Roman Numeral.
| Number | Conversion | Roman Numeral |
|---|---|---|
| 1 | I | |
| 3 | 1 + 1 + 1 | III |
| 5 | V | |
| 9 | 9 - 1 (not 5 + 4) | IX |
| 10 | X | |
| 19 | 10 + 9 = 10 + (10 - 1) | XIX |
| 20 | 10 + 10 | XX |
| 36 | 10 + 10 + 10 + 6 | XXXVI |
| 40 | 50 - 10 (not 10 + 10 + 10 + 10) | XL |
| 48 | 40 + 8 | XLVIII |
| 49 | 40 + 9 (not 50 -1) | XLIX |
| 50 | L | |
| 59 | 50 + 9 | LIX |
| 89 | 50 + 10 + 10 + 10 + 9 | LXXXIX |
| 99 | 90 + 9 = (100 - 10) + 9 (not 100 - 1) | XCIX |
| 100 | C | |
| 149 | 100 + 40 + 9 | CXLIX |
| 199 | 100 + 90 + 9 | CXCIX |
| 345 | 300 + 40 + 5 | CCCXLV |
| 499 | 400 + 90 + 9 = (500 - 100) + 90 + 9 | CDXCIX |
| 894 | 800 + 90 + 4 = (500 + 300) + 90 + 4 | DCCCXCIV |
| 900 | 1000 - 100 | CM |
| 999 | 900 + 90 + 9 = (1000 - 100) + 90 + 9 | CMXCIX |
| 1000 | M | |
| 1990 | 1000 + 900 + 90 | MCMXC |
| 1999 | 1000 + 900 + 90 + 9 | MCMXCIX |
| 2010 | 2000 + 10 | MMX |
Ok, we have set the foundation, now it is easy to convert larger numbers like 5000 or above into the Roman Numeral System.
| Number | Roman Numeral | Number | Roman Numeral |
|---|---|---|---|
| 5 | V | 5000 | V |
| 10 | X | 10,000 | X |
| 50 | L | 50,000 | L |
| 100 | C | 100,000 | C |
| 500 | D | 500,000 | D |
| 1,000 | M | 1,000,000 | M |
Let's convert these numbers
| Number | Conversion | Roman Numeral |
|---|---|---|
| 5,001 | 5000 + 1 | VI |
| 5,100 | 5000 + 100 | VC |
| 9,599 | 9000 + 500 + 99 | IXDXCIX or MXDXCIX |
| 9,999 | 9000 + 900 + 99 | IXCMXCIX or MXCMXCIX |
| 40,000 | XL | |
| 49,500 | 49,000 + 500 | XLD |
| 250,589 | 250,000 + 500 + 89 | CCLDLXXXIX |
| 999,999 | 900,000 + 90,000 + 9,000 + 900 + 90 + 9 | CMXCIXCMXCIX |