The diameter of the outlet of a piece of toothpaste is 5mm, and each time you squeeze 1cm of toothpaste, you can use it 40 times. What is the volume of this toothpaste in cubic millimeters?
一只牙膏的出口处直径为5mm，每次挤1cm长的牙膏，可以用40次，这支牙膏的容积是多少立方毫米？
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) ** 2</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">1 * 10 * 40</gadget>
<output>400</output>

<gadget id="calculator">3.14 * (25/4) * 400</gadget>
<output>7_850</output>

<result>7_850</result>