Uncle Wang went to Shanghai for a business trip on April 27th, and came back at the end of the month. How many days did Uncle Wang go on business?
王叔叔4月27号去上海出差，月底回来，王叔叔出差了多少天．
<gadget id="calculator">30 - 27</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>