How many circles with a radius of 2 cm can be drawn on a square paper with a side length of 20 cm? (both sides can be painted)
在一张边长是20厘米的正方形纸上，画半径是2厘米的圆，最多可以画几个？(正反面都可以画)
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

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

<gadget id="calculator">5 * 5 * 2</gadget>
<output>50</output>

<result>50</result>