My Casio calculator shows 9 when I explicit write the * sign: 6/2*(1+2) and 1 when I write the same expression with implicit multiplication: 6/2(1+2). The first case the calculation is done from "left to right", the other from "right to left", hmm...

There is no ambiguity if you do your calculation from "left to right" whenever operations have the same "hierarchical power" which is the case for multiplication and division. That's the way I learned arithmetic; and thus I join the "9-people" :-)