missing units after compilation 

```less
@var1: 2em;
@var2: 1/2em;

#myClass{
width: @var1*@var2 ;
}
```

Output for this is:
```css
#myClass {width: 1em};
```

But if we interchange the variables as:
```css
#myClass{
width: @var2*@var1;
}
```

Output for this is:
```css
#myClass {width: 1};
```

`em` is missing. :(