Step 1: Take the center point of the height of the cake, make the first plane cut, and divide the cake into two equal layers.

Step 2: cut the second knife in the middle of the upper dot, and cut the upper layer of the cake in half.

Step 3: Take the center point of the upper layer, cut the third knife vertically and straight through the second knife, and divide the upper layer of the cake into four pieces on average.

Step 4: Because every step is equally divided, the divided cake has four pieces of equal size on the top and the same on the bottom, and it is finished by cutting eight pieces with three knives.