Simple calculation: 3620-1-2-3-…-76-77-78-79.
简算：3620-1-2-3-…-76-77-78-79．
<gadget id="calculator">1 + 79</gadget>
<output>80</output>

<gadget id="calculator">79 / 2</gadget>
<output>79/2 = around 39.5</output>

<gadget id="calculator">80 * (79/2)</gadget>
<output>3_160</output>

<gadget id="calculator">3_620 - 3_160</gadget>
<output>460</output>

<result>460</result>