Roman numerals originated in ancient Rome as a common method for counting and communicating. The system is based on seven basic symbols - I, V, X, L, C, D, and M - which are combined and subtracted to represent numbers. To convert Arabic numbers to Roman, larger place values are written first from left to right, and smaller numerals before larger ones indicate subtraction. A number cannot be repeated more than three times.

1. Roman Numerals

2. Roman numerals originated in
ancient Rome. The numerals developed
out of a need for a common method of
counting, essential to communications
and trade. A counting system was
devised based on a person's hand.

3. There are seven basic symbols:
I, V, X, L, C, D and M.

5. How to convert Arabic numbers to
Roman Numerals ?
Roman Numerals are made up by
adding or subtracting numbers like this:
11=10+1 = XI 9 = 10 – 1 = IX
40 = 50 –10 = XL

6. Roman numbers are written by
combining the seven numbers listed in
the table.
Examples: VII is 5 + 1 + 1 = 7.
XIII is 10 + 1 + 1 + 1 = 13.

7. If you want to convert 1,100 in
Roman Numerals, use M for 1000 and then
put a C after it for 100; 1,100 = MC
900 =1000 – 100
so the C comes before M = CM

8. If a smaller number comes before
a larger number, you subtract the
smaller from the larger.
Examples: IV is 5 ̶ 1 = 4.
IX is 10 ̶ 1 = 9.

9. Only one digit is subtracted at one
time. So, you can't represent 8 as IIX
because that's subtracting one from ten
twice. Rather, you'd write VIII. XLIV is
considered adding (50 ̶ 10) to (5 ̶ 1), or 44,
so that's okay. Examples: CIV is 100 + (5 ̶ 1)
= 104. LIX is 50 + (10-1) = 59.

10. The V is never subtracted. The
number 45 is written as XLV, not
VL.

11. A roman number cannot be repeated
more than three times.
4 is not IIII but IV (5-1 =4)
400 is not CCCC but CD (500-100 = 400)
54 is not LIIII but LIV (50+4 = 54)

12. Some more examples:
VIII = 5+3 = 8
XIX = 10+ 9 = 19
(Remember 9 is always = IX (1 less
than 10)
XL = 50-10 = 40
XC = 100-10 = 90

13. Try these:
7 =
12 =
15 =
20 =