The watch factory wants to produce a batch of watches. The original plan is to produce 672 watches per day, which takes 15 days to complete. It was actually completed 3 days ahead of schedule. How many more pieces are actually produced per day than the original plan?
手表厂要生产一批手表，原计划每天生产672只，15天完成．实际提前3天完成，实际每天比原计划多生产多少只？
<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">15 / 12</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">672 * (5/4)</gadget>
<output>840</output>

<gadget id="calculator">840 - 672</gadget>
<output>168</output>

<result>168</result>