数学公式不输出我想要的结果

The purpose of the program is to calculate the volume at each depth. The inputs are the radius and length and in this test case they are 2.1 and 5.6 respectively. I keep getting 0, 1, 2, 3, and 4 for my volume but that's not the right volume, the depth/height is correct so perhaps someone can shed light on whats wrong with my equation below?The purpose of the program is to calculate the