The height of a floor is about 3m. If the ground floor is the first floor and Xiaohua lives on the eighth floor, how many meters is the floor of his house from the ground?
一层楼的高度大约是3m，如果底楼为第1楼，小华住在第8楼，他家地板离地面大约有多少m．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<result>21</result>