Computing with units

### 5.1.2 Computing with units

`Xcas` performs usual arithmetic operations (+, -, *, /, `^`) on unit objects. Different units may be used, but they must be compatible for + and -. The result is an unit object

- for the multiplication and the division of two unit objects `_u1` and `_u2` the unit of the result is written `_(u1*u2)` or `_(u1/u2)`.
- for an addition or a substraction of compatible unit objects, the result is expressed with the same unit as the first term of the operation.

Input :

`1_m+100_cm`

Output :

`2_m`

Input :

`100_cm+1_m`

Output :

`200_cm`

Input :

`1_m*100_cm`

Output :

`1_m```^```2`