How many two-digit decimals are there greater than 0.3 and less than 0.5?
大于0.3而小于0.5的两位小数有多少个．
<gadget id="calculator">49 - 31</gadget>
<output>18</output>

<gadget id="calculator">18 + 1</gadget>
<output>19</output>

<result>19</result>