There are 16 steps to go up each floor. How many steps does the owner who lives on the fifth floor have to walk down to the first floor?
每上一层楼要走16级台阶，家住五楼的业主下到一楼要走多少级台阶．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">16 * 4</gadget>
<output>64</output>

<result>64</result>