Uncle Niu rides a bicycle across a bridge with a length of 816.4 meters. It is known that the diameter of the wheels is about 0.65 meters, and the wheels rotate an average of 100 times per minute. How many minutes does it take for Uncle Niu to cross the bridge?
牛叔叔骑自行车通过一座长816.4米的大桥，已知车轮的直径约是0.65米，车轮平均每分钟转100圈，则牛叔叔通过这座大桥需要多少分钟？
<gadget id="calculator">3.14 * 0.65</gadget>
<output>2.041</output>

<gadget id="calculator">2.041 * 100</gadget>
<output>204.1</output>

<gadget id="calculator">816.4 / 204.1</gadget>
<output>4</output>

<result>4</result>