Cut it first, whatever you want, then overlap it and cut it again, and it's eight pieces. That is, tofu is divided into two pieces with one knife. Then two pieces of tofu are stacked, and the second knife cuts down. When cutting to the second floor, put the two pieces of tofu cut from the top under the second piece of tofu, and when cutting the tofu from the second floor, put the two pieces of tofu cut from the second floor under the two pieces of tofu. In the process of putting tofu in the middle, keep the knife from leaving the tofu, so there are eight pieces. And so on, you can continue to cut into n pieces.

This is an Olympic math problem, which mainly examines thinking ability and flexibility.

Another way is to use a cross-shaped knife, which is cross-shaped. If you cut it with one knife, it will be four pieces. How much can you cut with two knives? Anyway, eight dollars is ok.

In fact, there is no fixed answer to this question, which can spread your thinking ability. Tofu has no restrictions on tofu and knives have no restrictions on knives, so everything is possible.