An object falls from a high altitude, falls 5.2 meters in the first second, and the falling distance increases by 10.4 meters in each second from the previous second, and lands in 25 seconds, how many kilometers is the object from the ground before falling?
一个物体从高空下落，第一秒落下5.2米，以后每一秒下落的距离均比前一秒增加10.4米，25秒落地，这个物体在下落前距地面多少千米？
<gadget id="calculator">25 - 1</gadget>
<output>24</output>

<gadget id="calculator">10.4 * 24</gadget>
<output>249.6</output>

<gadget id="calculator">5.2 + 249.6 + 5.2</gadget>
<output>260</output>

<gadget id="calculator">25 / 2 / 1_000</gadget>
<output>1/80 = around 0.0125</output>

<gadget id="calculator">260 * (1/80)</gadget>
<output>13/4 = around 3.25</output>

<result>13/4 = around 3.25</result>