# Can you count with Roman numerals?

### Numbers and digits

Thousands of years ago humans used numbers.

Numbers were important to people thousands of years ago, but the symbols for numbers are very different.

### Old numerals

Here is some background information:

**Egyptian numbers**5000 years ago- Numbers of
**Maya**about 3000 years ago - Interesting: the numbers we use come from the Arabic script. Numbers from India are used in the Arabic script.
- Arabic numbers came to Europe in the 12th century.

### Roman numerals

About 2000 years ago, the ruled in Europe and around the Mediterranean **Romans**. They had special numerals and methods of writing the numbers.

Even when the Roman Empire ceased to exist and centuries later, Roman numerals were used. Til today!

Here you can find Roman numbers:

- for dates on old buildings

Image: Studio Schmidt-Lohmann

- in History of Differentiating Emperors and Kings: Frederick II (Frederick the Second) or Henry VIII (Henry the Eighth - of England)

- on clock faces

Image: fotolia.com (Tina Binder)

Roman numbers are numbers that the Romans used around 2000 years ago. However, these characters for numbers are much older, but were still widespread in Europe in the 16th century.

### The numerals (digits) of the Romans

Numbers are mostly written using characters, the digits.

There are **seven roman numerals**. You differentiate between **four basic digits** and **three intermediate digits**.

### Basic digits

### Intermediate digits

In contrast to the numerals in the tens system, the Roman numerals always have the same value.

The Roman **Digits** have regardless of their position in the number **always the same value**.

This is different from our number system. With us, the number 1 can be a thousand or a hundred.

- Our
**Decimal system**is a place value system made up of 10 digits (0 to 9). Depending on where the digit is located, it has a certain value (ones, tens, hundreds, etc.). - For the
**zero**there is no sign! In a text, the Romans marked them with a "space" or with the "nullum" (Latin "null")

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### How digits become numbers

The composition of the digits into one **roman numeral** is completely different from the ones you know **Numbers in the tens system**.

### Basic rules (addition rules)

- The numbers are read from left to right.
- Basic digits can appear several times. Intermediate digits can only appear once.
- The value of the digits decreases from left to right.
- Add up the basic digits and intermediate digits.

**Examples**

- XXVI = 10 + 10 + 5 + 1 = 26
- III = 1 + 1 + 1 = 3
- XIII = 10 + 1 + 1 = 13
- MCCV = 1000 + 100 + 100 + 5 = 1205

The value of the digits decreases from right to left and the values are added.

In comparison, a number in our system of ten:**example**: 26 = 2·10 + 6 ·1 = 20 + 6 = 26

### That was not all

### Further rules (subtraction rules)

- Basic digits may appear next to each other a maximum of 3 times (sometimes 4 times).
**example**CCCIII = 100 + 100 + 100 + 1 + 1 + 1 = 303 - Smaller basic digits to the left of larger basic or intermediate digits are subtracted.
**example**

IX =**10 -1**= 9; XL =**50 - 10**= 40 - Intermediate digits may not be subtracted.
- The basic digits I, X and C may only be subtracted from the next higher basic or intermediate digit (
*not always applied*).**example**

99 is not IC,

but 99 = XCIX = (100 - 10) + (10 - 1) = 90 + 9

**Further examples**

- IX = 10 - 1 = 9
- CD = 500-100 = 400
- CMIX = (1000-100) + (10-1) = 900 + 9 = 909

You subtract the smaller digits on the left from the larger digits on the right.

The subtraction rule for shortening the spelling of Roman numbers existed 2000 years ago, but was not applied consistently.

### Did you know?

- The largest number that can be represented using Roman numerals is 3999.
- In the tens system, a number with more digits is always larger than a number with fewer digits (e.g. 340 <3400). This does not apply to Roman numerals (e.g. IV
- There are numbers that have the same number in the Arabic and Roman representation (e.g. 11 and XI).
- Two interesting representations: 51 and VI.
- IV often stands for IIII on clock faces.

*kapiert.de*can do more:

- interactive exercises

and tests - individual classwork trainer
- Learning manager

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