△○△○△○△…△○△As shown in the figure, there is a ○ in the middle of every two △. A total of 30 ○ are placed like this, how many △ are needed to be placed?
△○△○△○△…△○△如图，每两个△中间有一个○．像这样一共摆了30个○，需要摆多少个△．
<gadget id="calculator">30 + 1</gadget>
<output>31</output>

<result>31</result>