Ask: What is the sum of all the numbers in these natural numbers from 1 to 1989.
求：1到1989这些自然数中的所有数字之和是多少．
<gadget id="calculator">2_000 / 2</gadget>
<output>1_000</output>

<gadget id="calculator">28 * 1_000</gadget>
<output>28_000</output>

<gadget id="calculator">19 + 28</gadget>
<output>47</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">47 * 5</gadget>
<output>235</output>

<gadget id="calculator">28_000 - 235</gadget>
<output>27_765</output>

<result>27_765</result>