Li Ming went to his grandmother's house during the summer vacation. He arrived at his grandmother's house on the morning of July 15th and left his grandmother's house on the evening of August 10th. How many days did he stay at grandma's house?
李明暑假里到外婆家度假．他是7月15日早晨到外婆家，8月10日晚上离开外婆家的．他在外婆家一共多少天？
<gadget id="calculator">31 - 15</gadget>
<output>16</output>

<gadget id="calculator">16 + 1 + 10</gadget>
<output>27</output>

<result>27</result>