1, table problem: a square table, cut off one corner, how many corners are left.

2, cut tofu problem: a piece of tofu cut three knives, can be cut into a few pieces at most.

3, the problem of cutting watermelon: a watermelon is cut into seven parts with three knives, and the remaining eight skins are eaten. How?

Mathematics is a subject that studies concepts such as quantity, structure, change, space and information. Mathematics is a universal means for human beings to strictly describe and deduce the abstract structure and mode of things, and can be applied to any problem in the real world. All mathematical objects are artificially defined in essence. In this sense, mathematics belongs to formal science, not natural science. Different mathematicians and philosophers have a series of views on the exact scope and definition of mathematics. Mathematics plays an irreplaceable role in the development of human history and social life, and it is also an indispensable basic tool for studying and studying modern science and technology.