A set of numbers arranged regularly: 23, 27, 31, 35, .... What is the sum of the first 20 numbers in this column?
有规律排列的一组数：23、27、31、35、…．则这列数前20个数的和为多少．
<gadget id="calculator">23 * 20</gadget>
<output>460</output>

<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">20 * 19 * 2</gadget>
<output>760</output>

<gadget id="calculator">460 + 760</gadget>
<output>1_220</output>

<result>1_220</result>