Division (mathematics)

Division is one of the four basic operations of arithmetic, the others being addition, subtraction, and multiplication. Several symbols are used for the division operator, including the obelus (÷), the colon (:) and the slash (/).Addition (+)Subtraction (−)Multiplication (× or ·)Division (÷ or /) Division is one of the four basic operations of arithmetic, the others being addition, subtraction, and multiplication. Several symbols are used for the division operator, including the obelus (÷), the colon (:) and the slash (/). At an elementary level the division of two natural numbers is – among other possible interpretations – the process of calculating the number of times one number is contained within another one.:7 This number of times is not always an integer, and this led to two different concepts. The division with remainder or Euclidean division of two natural numbers provides a quotient, which is the number of times the second one is contained in the first one, and a remainder, which is the part of the first number that remains, when in the course of computing the quotient, no further full chunk of the size of the second number can be allocated. For a modification of this division to yield only one single result, the natural numbers must be extended to rational numbers or real numbers. In these enlarged number systems, division is the inverse operation to multiplication, that is a = c ÷ b means a × b = c, as long as b is not zero. If b = 0, then this is a division by zero, which is not defined.:246 Both forms of divisions appear in various algebraic structures. Those in which a Euclidean division (with remainder) is defined are called Euclidean domains and include polynomial rings in one indeterminate. Those in which a division (with a single result) by all nonzero elements is defined are called fields and division rings. In a ring the elements by which division is always possible are called the units (for example, 1 and –1 in the ring of integers). In its simplest form, division can be viewed either as a quotition or a partition. In terms of quotition, 20 ÷ 5 means the number of 5s that must be added to get 20. In terms of partition, 20 ÷ 5 means the size of each of 5 parts into which a set of size 20 is divided. For example, 20 apples divide into four groups of five apples, meaning that twenty divided by five is equal to four. This is denoted as 20 / 5 = 4, 20 ÷ 5 = 4, or 20/5 = 4. Notationally, the dividend is divided by the divisor to get a quotient. In the example, 20 is the dividend, 5 is the divisor, and 4 is the quotient. Unlike the other basic operations, when dividing natural numbers there is sometimes a remainder that will not go evenly into the dividend; for example, 10 ÷ 3 leaves a remainder of 1, as 10 is not a multiple of 3. Sometimes this remainder is added to the quotient as a fractional part, so 10 ÷ 3 is equal to 3 1/3 or 3.33..., but in the context of integer division, where numbers have no fractional part, the remainder is kept separately or discarded. When the remainder is kept as a fraction, it leads to a rational number. The set of all rational numbers is created by every possible division using integers. In modern mathematical terms, this is known as extending the system. Unlike multiplication and addition, Division is not commutative, meaning that a ÷ b is not always equal to b ÷ a. Division is also not, in general, associative, meaning that when dividing multiple times, the order of division can change the result. For example, (20 ÷ 5) ÷ 2 = 2, but 20 ÷ (5 ÷ 2) = 8 (where the use of parentheses indicates that the operations inside parentheses are performed before the operations outside parentheses). Division is, however, distributive, in the sense that (a+b) ÷ c = (a ÷ c) + (b ÷ c) for every number. Specifically, division has the right-distributive property over addition and subtraction. That means: