A piece of rectangular paper with a length of 28 cm and a width of 21 cm can be cut into how many circular pieces of paper with a radius of 3.5 cm at most.
一张长28厘米、宽21厘米的长方形纸，最多能剪成多少个半径是3.5厘米的圆形纸片．
<gadget id="calculator">3.5 * 2</gadget>
<output>7</output>

<gadget id="calculator">21 / 7</gadget>
<output>3</output>

<gadget id="calculator">28 / 7</gadget>
<output>4</output>

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

<result>12</result>