Xiao Ming lives on the 6th floor. He walked up 30 steps from the 1st floor to the 3rd floor. How many steps does he have to climb to go upstairs?
小明家住6楼，他从1楼上到3楼一共走了30级台阶，他上一次楼，要爬多少级台阶．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<result>75</result>