The inner circumference of a track is 400m, the outer circle radius is 42m, and the inner circle radius is 40m. Xiaoyu and Xiaoke are running a 400m race. Xiaoyu is on the inside, the starting point is on the straight track, and the end point is the same. rice?
一条跑道的内侧周长是400m，外圈半径为42m，内圈半径为40m，小雨和小珂进行400m赛跑，小雨在内侧，起点在直道上，且终点相同，那么小珂应在小雨前多少米？
<gadget id="calculator">2 * 3.14 * 42</gadget>
<output>263.76</output>

<gadget id="calculator">2 * 3.14 * 40</gadget>
<output>251.2</output>

<gadget id="calculator">263.76 - 251.2</gadget>
<output>12.56</output>

<result>12.56</result>