[pdurrant]

Originally Posted by dreams

We use them (the round ones) for door stops, too..

My guess.

Spoiler:

It's a circle, so cut it in half, 1st cut.

Stack one half on top of the other half and cut it in half - 2nd cut.

Now you have 4, 1/4 pieces. Stack all the 1/4 th sized pieces on top of each other and make a 3rd cut.

Ta Da! you have 8, 1/8th pieces.

Well done Dreams, you have it right too.