In mathematics, a multiple is the product of any quantity and an integer). For example, if we have two quantities a and b, we can say that b is a multiple of a if b = na for some integer n, which is called the multiplier. If a is not zero, this is equivalent to saying that b/a is an integer). When a and b are both integers, and b is a multiple of a, then a is called a divisor of b. One says also that a divides b). Multiples are useful when organizing a number into groups, and they are the answers within any set of times tables. For example, 25 is a multiple of 5, and 14 is a multiple of 7. A secure knowledge of multiplication facts is essential in calculating multiples.