Put a row of chrysanthemums in the corridor of the school, put a pot every 1 meter (both ends are placed), the corridor is 20 meters long, how many pots of chrysanthemums need to be placed.
在学校走廊上放一排菊花，每隔1米放1盆(两端都放)，走廊长20米，需要放多少盆菊花．
<gadget id="calculator">20 / 1</gadget>
<output>20</output>

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

<result>21</result>