Книга: Square pyramidal number: Mathematics, Figurate Number, Pyramid, Mathematical Induction, Fibonacci, Liber Abaci, Faulhaber's Formula, Tetrahedral Number, Squared Triangular Number

High Quality Content by WIKIPEDIA articles! In mathematics, a pyramid number, or square pyramidal number, is a figurate number that represents a pyramid with a base and four sides.Pyramid numbers can be modelled in physical space with a given number of balls and a square frame that hold in place the number of balls forming the base, that is, n2. They also solve the problem of counting the number of squares in an n ? n grid. In mathematics, a square number, sometimes also called a perfect square, is an integer that can be written as the square of some other integer in other words, it is the product of some integer with itself. So, for example, 9 is a square number, since it can be written as 3 ? 3. Square numbers are non-negative. Another way of saying that a (non-negative) number is a square number, is that its square root is again an integer. For example, ?9 = 3, so 9 is a square number.