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Roman Numeral Rules
Four Basic Principles for Reading and Writing Roman Numerals
Question | Answer |
---|---|
A letter repeats its value that many times and can only be repeated three times | XXX=30, CC=20 |
If one or more letters are placed after another letter of greater value, add that amount. | VI=6 (5+1=6) LXX=70 (50+10+10=70) MCC=1200 (1000+100+100=1200) |
If a letter is placed before another letter of greater value, subtract that amount. | IV=4 (5-1=4) XC=90 (100-10=90) |
ONLY subtract powers of ten. | XCV=95 (90+5) DO NOT SUBTRACT 5 from 100!! |
Only subtract one number from another | XIII=13 (10+3) don't subtract 2 from 15 |
do not subtract a number from one that is more than 10 times greater | XCIX=99 (90+9) |
a bar placed on top of a letter or string of letters increases the value by 1000 | XV=15,if it had lines over top of the letters it would = 15000 |