An electronics factory produced 420 computers in October, and the number of computers produced in September was October (9/10). How many computers were produced in September?
某电子厂十月份生产电脑420台，九月份生产的台数是十月份的(9/10)，九月份生产电脑多少台．
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">420 * (9/10)</gadget>
<output>378</output>

<result>378</result>