The area of the parallelogram and the triangle are equal, the base of the parallelogram is 1/2 of the base of the triangle, and the height of the triangle is equal to the height of the parallelogram.
平行四边形和三角形面积相等，平行四边形的底是三角形底的(1/2)，三角形的高是平行四边形高的多少．
<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">2 / 2 / 1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 2 / 1</gadget>
<output>1</output>

<gadget id="calculator">4 * (1/4) * 1</gadget>
<output>1</output>

<result>1</result>