Put a potted flower every 2 meters on both sides of a 40-meter-long road (both ends), how many potted flowers should be placed in total.
在一条长40米的道路两边每隔2米放一盆花(两头都放)，一共需放多少盆花．
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<result>42</result>