In a six-story building, there are 20 stairs between each floor. How many stairs do you need to walk from the downstairs to the 5th floor?
一幢六层楼，每层之间有20级楼梯，从楼下走到5层，要走多少级楼梯？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">4 * 20</gadget>
<output>80</output>

<result>80</result>