Clever calculation: 78*126+78*24-50*78.
巧算：78*126+78*24-50*78．
<gadget id="calculator">78 * 126</gadget>
<output>9_828</output>

<gadget id="calculator">78 * 24</gadget>
<output>1_872</output>

<gadget id="calculator">50 * 78</gadget>
<output>3_900</output>

<gadget id="calculator">1_872 - 3_900</gadget>
<output>-2_028</output>

<gadget id="calculator">9_828 + (-2_028)</gadget>
<output>7_800</output>

<result>7_800</result>