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### Roman numerals

In the past, roman numerals were used. You count therein as follows

 Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ Ⅷ Ⅸ Ⅹ

what corresponds to the Arabic numerals

 1 2 3 4 5 6 7 8 9 10

##### Zero

There is no digit for 0 (Latin: nulla). There's been discussion for centuries whether or not 0 is a number. Today we call it a number, and for writing decimal numbers we need it.

##### Large numbers

The Romans had no decimal system and formed numbers by combining the different symbols.

 0 1 2 3 4 5 6 7 8 9 10 11 12 13 I II III IV V VI VII VIII IV X XI XII XIII

 10 20 30 40 50 60 70 80 90 X XX XXX XL L LX LXX LXXX XC

 100 500 1 000 C D M

 1 000 5 000 10 000 50 000 100 000 ↀ ↁ ↂ ↇ ↈ

##### IIII

Sometimes you will see roman numerals as decoration on buildings. On analog clocks, the hours are usually indicated with roman numerals. The number is almost always shown as ⅡⅡ. Because roman numerals have no symbol for 0, you start with .

 Ⅻ ⅩⅠ Ⅰ Ⅹ ⅠⅠ Ⅸ Ⅲ Ⅷ ⅠⅠⅠⅠ Ⅶ Ⅵ Ⅴ

##### History

The American mathematician Claude Shannon (1916 - 2001) invented a computer with roman numerals called THROBAC.