I am realy sorry to ask so simple question, but I realy can't figure out what is the problem.
I want to convert any mark to 12 grade scale. I am trying to this as following:

```
double coef=(4/20)*12;
int mark=(int)coef;

```

But when i execute this code via debugger I see that `coef` is equal to zero. Why if this is double variable?