The sequence 2, 5, 8, ... has a total of 21 numbers, so what is the last number?
数列2、5、8、…一共有21个数，那么最后一个数是多少．
<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">3 * 11</gadget>
<output>33</output>

<gadget id="calculator">2 + 33</gadget>
<output>35</output>

<result>35</result>