Master Liu made a batch of parts. On the first day, he made 30 parts. After that, he made 2 more parts every day than the previous day. On the 15th day, he made 48 parts, which was just finished. How many parts are there in this batch?
刘师傅做一批零件，第一天做了30个，以的每天都比前一天多做2个，第15天做了48个，正好做完．这批零件共有多少个？
<gadget id="calculator">14 - 1</gadget>
<output>13</output>

<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<gadget id="calculator">30 + 30 + 26</gadget>
<output>86</output>

<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<gadget id="calculator">86 * 7</gadget>
<output>602</output>

<gadget id="calculator">602 + 48</gadget>
<output>650</output>

<result>650</result>