# Roman numbers

This calculator transforms roman numbers into arabic numbers and vice versa.
The romans used those numbers: I=1, V=5, X=10, L=50, C=100, D=500 and M=1000. In most cases, they were simply put behind each other and added. Exception: If one letter stands to the left of a letter with a higher value, you subtract the value of that letter.

## How did the Romans write numbers?

The Romans did not know our number system with 10 digits (we got from the Arabians). Therefore, the romans wrote numbers by writing letters.

## What number signs did the Romans know?

The Romans used the signs I for 1, V for 5, X for 10, L for 50, C for 100, D for 500 and M for 1000.

## How to keep those signs in mind?

Simply remember the I, the X, the C, the D and the M. The I is simply a line. C and M are corresponding to the latin words centum (hundred) and mille (thousand). If you remember the X, the V is simply the upper half of the X and the L is the lower half of the C.

## How to put those numbers together?

Normally, you just put signs behind each other, and the sum corresponds to the number.
Exception: To avoid having more than tree times the same sign in a row, use this notation: If a sign of less worth is before a sign of higher worth, subtract its value.

## How did the Romans add or subtract numbers?

There were difficult algorithms for adding or subtracting. This is one of the main reason why we use arabian numbers nowadays and not the roman ones.

## Roman numbers

Mathepower can transform roman numbers into arabian numbers and vice versa. Just enter a number and it will be transformed.