△○△○△○△○…△○△ There are 20 △ in total, and there is a ○ in between every two △, how many ○ in total?
△○△○△○△○…△○△中共有20个△，每两个△中间有一个○，一共有多少个○．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<result>19</result>