I have 30 yuan, envelopes are 50 cents each, how many can I buy?
我有30元，信封5角一个，能买多少个？
<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<result>60</result>