An object falls from a high altitude. It is known that the falling distance in the first second is 4.9 meters, and the falling distance in each second is 9.8 meters more than the previous one. After 40 seconds, the object falls to the ground. How far was the object from the ground before it fell?
一个物体从高空下落，已知第一秒钟下落的距离是4.9米，以后每秒钟落下的距离都比前一钞钟多9.8米，40秒钟后，物体落地．这个物体在下落前距地面多少米？
<gadget id="calculator">40 - 1</gadget>
<output>39</output>

<gadget id="calculator">39 * 9.8</gadget>
<output>382.2</output>

<gadget id="calculator">4.9 + 382.2</gadget>
<output>387.1</output>

<gadget id="calculator">4.9 + 387.1</gadget>
<output>392</output>

<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">392 * 20</gadget>
<output>7_840</output>

<result>7_840</result>