Find the sum of 111+112+113+...+288+289.
求111+112+113+…+288+289的和．
<gadget id="calculator">111 + 289</gadget>
<output>400</output>

<gadget id="calculator">179 / 2</gadget>
<output>179/2 = around 89.5</output>

<gadget id="calculator">400 * (179/2)</gadget>
<output>35_800</output>

<result>35_800</result>