$$12 \times \left( \frac{1}{2} \times \frac{1}{3} \times \frac{1}{4}\right)=$$． 
Overseas Competition->Knowledge Point->Calculation Modules->Fractions->Operations of Fractions
$$12 \times \left( \frac{1}{2} \times \frac{1}{3} \times \frac{1}{4}\right)$$  $$=\left(12 \times \frac{1}{2}\right) \times \frac{1}{3} \times \frac{1}{4}$$  $$=6 \times \frac{1}{3} \times \frac{1}{4}$$  $$=2 \times \frac{1}{4}$$  $$= \frac{2}{4}$$  $$=\frac{1}{2}$$. 