Guoguo started to plant trees on the Arbor Day every year since the third grade of elementary school. He planted 2 trees in the third grade, and every year since then he has planted 2 more trees than the previous year. So, how many trees did Guoguo plant when he graduated from high school?
果果从小学三年级开始每年的植树节时都植树，三年级时植了2棵，以后每年都比前一年多植树2棵．那么，果果高中毕业时一共植树多少棵．
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">10 * 9 * 1</gadget>
<output>90</output>

<gadget id="calculator">20 + 90</gadget>
<output>110</output>

<result>110</result>