4 hours and 30 minutes = how many hours.
4小时30分=多少小时．
<gadget id="calculator">30 / 60</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) + 4</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>