A: Cut a cake six times, and divide it into 22 pieces at most.

Solution: (at the end of the figure)

This is actually a problem of "multiple straight lines in the plane intersect".

If you want to cut the most copies in a certain number of times, you must meet the following two conditions:

First, make sure that each line intersects any other line. Second, make sure that any intersection does not coincide with any other intersection (that is, only two straight lines can be found along any intersection).

Law summary: As can be seen from the following figure, when cutting for the first time, it can be divided into 2 parts at most; The second time can be divided into up to 4 pieces; The third time can be divided into up to 7 pieces; The fourth time can be divided into 1 1 block at most; The fifth time can be divided into 16 at most; The sixth time can be divided into 22 blocks at most ... The nth time can be divided into 1/2 (n 2+n+2) at most.

Figure: