A factory produces a kind of parts. It is calculated that the production of 60 parts per day can be completed within the planned time. The actual production of 100 parts per day is completed 6 days ahead of schedule. How many parts are there in this batch?
某工厂生产一种零件，计算每天生产60个，可以在计划时间内完成，实际每天生产100个，结果提前6天完成，这批零件共有多少个？
<gadget id="calculator">100 * 6</gadget>
<output>600</output>

<gadget id="calculator">100 - 60</gadget>
<output>40</output>

<gadget id="calculator">600 / 40</gadget>
<output>15</output>

<gadget id="calculator">60 * 15</gadget>
<output>900</output>

<result>900</result>