## How did Roman Numerals begin?

Many people believe Roman Numerals began as a tally or marking system used by shepherds to keep track of how many sheep they had.
Each sheep was counted with a single notch cut into a stick with a knife. Every fifth sheep was recorded with two notches to form a V and then each tenth sheep was denoted by an X.
This method of record keeping was still being used by Italian shepherds in the nineteenth century.
The Basics

I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1000

The mnemonic 'I Value Xylophones Like Cows Do Milk' may really help you remember (Thanks to Adrian Bruce).

Put It Together

To write larger numbers in Roman numerals, Romans simply "added" all the symbols together. For instance:

LXXIII = 50 + 10 + 10 + 1 + 1 + 1 = 73
MDXII = 1000 + 500 + 10 + 1 + 1 = 1512

Hints:
- When writing roman numerals never use more than 3 of any symbol.
- When you have numerals on the right hand side of bigger ones, ADD.

Try these problems out (answers on the bottom)

1. Convert XXVIII to our number system
2. Convert XXXVI to our number system
3. What is LXII in our number system?
4. DCXXII =
5. MMXVI

When you have to Subtract

Sometimes you cannot follow the hint of not using more that 3 of any symbol, for instance in writing 9 in Roman numerals. Nine would be written VIIII, but that would break the rule of not using more than three I's. In these cases you need subtract the value of the smaller number from the larger.

IX = 10 - 1 = 9

Hint:
-When smaller numerals are on the left of larger ones... subtract.

Try these (answers on the bottom again):

1. IV =
2. VL =
3. CM =
4. XC =
5. CD =

Notable Roman Numeral Quote

'Class, please! If you don't learn roman numerals, you'll never know the date certain motion pictures were copyrighted.'
Edna Krabappel (from The Simpsons)

(Highlight the yellow answers to see clearly)Answers: 5. 2016 4. 622 3. 62 2. 36 1. 28
(Highlight again) 5. 400 4. 90 3.900 2. 45 1. 4