How many circles with a radius of 2 cm can be cut from a rectangular piece of paper with a length of 20 cm and a width of 12 cm.
在一张长20厘米，宽12厘米的长方形纸上，能剪多少个半径是2厘米的圆．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>