数学题：有一只圆柱形的玻璃杯，测得内直径是8cm，内装牛奶深度是6cm，正好是杯内容量的五分之四，再加多少毫升牛奶，才可以把杯子装满？

数学题解答：方法是先算出玻璃杯的容积，再乘（1- 4/5）。容积的算法与体积一样，都是用底面积乘高。

3.14×(8÷2)²×6×（1- 4/5）=60.288（毫升）

问题得以解决。

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