public double trocaOp(){
		switch(opVal){
		case 10:
			if(Double.isInfinite(Factory.divisao(op1, op2))){
				err=true;
				div0=true;
			}
			return Factory.divisao(op1, op2);
		case 12: return Factory.multiplicacao(op1, op2);
		case 11: return Factory.subtraccao(op1, op2);
		case 15: return Factory.soma(op1, op2);
		}
		return 0;
	}