Arithmetic sequence: 30, 34, 38, 42, ... what is the 62nd item.
等差数列：30、34、38、42、…的第62项是多少．
<gadget id="calculator">62 - 1</gadget>
<output>61</output>

<gadget id="calculator">34 - 30</gadget>
<output>4</output>

<gadget id="calculator">61 * 4</gadget>
<output>244</output>

<gadget id="calculator">30 + 244</gadget>
<output>274</output>

<result>274</result>