Back to: Mathematics Primary 4
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Roman numerals use seven letters: I, V, X, L, C, D and M to represent the numbers 1, 5, 10, 50, 100, 500 and 1000. These seven letters make up thousands of numbers. Romans Numerals are based on the following symbols:
| 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
| I | V | X | L | C | D | M |
Basic Combinations
Which can be combined like this:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| I | II | III | IV | V | VI | VII | VIII | IX |
| 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 |
| X | XX | XXX | XL | L | LX | LXX | LXXX | XC |
| 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 |
| C | CC | CCC | CD | D | DC | DCC | DCCC | CM |
Forming Numbers – The Rules
When a symbol appears after a larger (or equal) symbol it is added
- Example: VI = V + I = 5 + 1 = 6
- Example: LXX = L + X + X = 50 + 10 + 10 = 70
But if the symbol appears before a larger symbol it is subtracted
- Example: IV = V − I = 5 − 1 = 4
- Example: IX = X − I = 10 − 1 = 9
To Remember: After Larger is Added
Don’t use the same symbol more than three times in a row (but IIII is sometimes used for 4, particularly on clocks)
How to Convert to Roman Numerals
Break the number into Thousands, Hundreds, Tens and Ones, and write down each in turn
Example: Convert 1984 to Roman Numerals.
Break 1984 into 1000, 900, 80 and 4, then do each conversion
- 1000 = M
- 900 = CM
- 80 = LXXX
- 4 = IV
1000 + 900 + 80 + 4 = 1984, so 1984 = MCMLXXXIV
How To Remember
Think “MeDiCaL XaVIer”.
It has the roman numerals in descending order from 1000 to 1.
I, for one, like Roman numerals!
Really Big Numbers
Numbers greater than 1,000 are formed by placing a dash over the symbol, meaning “times 1,000”, but these are not commonly used:
| 5,000 | 10,000 | 50,000 | 100,000 | 500,000 | 1,000,000 |
| V | X | L | C | D | M |
i-1 vi-6 xi-11 xvi-16 xxiv-24 L-50 cc-200
ii-2 vii-7 xii-12 xvii-17 xxix-29 Lv-55 ccc-300
iii-3 viii-8 xiii-13 xviii-18 xxxix-39 xc-90 CD-400
iv-4 ix-9 xiv-14 xix-19 xL-40 xcvi-96 CDXL-440
v-5 x-10 xv-15 xx-20 xLv-45 c-100 CDL-450
D-500 DCC-700 CM-900 M-1000 MMM-3000
IV-4000 IVD-4500 V-5000 VM-6000 X-10000
L-5000 C-100000 D-500000 M-1000000
Application of Roman figures
LXX +MC =MCLXX
CCCIX +DIV = DCCCXIII
MCMXCIX + DI = MMD
XXXII – XIX = XIII
MC –III = MXCVII
CCC × X = MMM
XXV × XXV = DCXXV
CCCLXXV ÷ V = LXXV
MM ÷ XL = L
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