省艺术宫里面有8根圆柱，每根柱子的底面半径是0.35m，高是30m。先要给这些柱子涂上油漆，如果每平方米用油漆0.25kg，共需油漆多少千克？

数学题解答：需用油漆多少千克和柱子涂油漆的面积有关。柱子上顶天，下立地，所以只有侧面能被涂上颜色。只需算出一根柱子的侧面积，再乘上8，就知道了所有柱子涂油漆的面积，进而可以求出油漆的重量。

侧面积：3.14×0.35×2×30＝65.94（平方厘米）

涂油漆总面积：65.94×8＝527.52（平方厘米）

油漆重量：527.52×0.25＝131.88（kg）

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