Division (mathematics)

<math>20: 4=5</math>

In mathematics, the word "division" means the operation which is the opposite of multiplication. The symbol for division can be a slash, a line, or the division sign (<math>\div</math>), as in:

<math>6/3\,</math>    or    <math>\frac 63</math>    or    <math>6 \div 3.</math>

Each, of those three, means "6 divided by 3" giving 2 as the answer. The first number is the dividend (6), and the second number is the divisor (3). The result (or answer) is the quotient. Whole numbers, any left-over amount is called the "remainder" (such as 14/4 gives 3 with the remainder as 2, as the number Template:Convert/numdisp, same as Template:Convert/numdisp or 3.5).

The numbers can be very big, such as with two hundred: 200/5 = 40, or with 7 billion:  7,000,000,000 / 1000 = 7,000,000 (equals 7 million).

With multiplication

If c times b equals a, written as:

<math>c \times b = a</math>

where b is not zero, then a divided by b equals c, written as:

<math>\frac ab = c</math>

For instance,

<math>\frac 63 = 2</math>


<math>2 \times 3 = 6</math>.

In the above expression, a is called the dividend, b the divisor and c the quotient.

Division by zero

<math>\frac x0 = ?</math>

...is not defined.


Division is most often shown by placing the dividend over the divisor with a horizontal line, also called a vinculum, between them. For example, a divided by b is written

<math>\frac ab.</math>

This can be read out loud as "a divided by b" or "a over b". A way to express division all on one line is to write the dividend, then a slash, then the divisor, like this:


This is the usual way to specify division in most computer programming languages since it can easily be typed as a simple sequence of characters.

A typographical variation which is halfway between these two forms uses a slash but elevates the dividend, and lowers the divisor:

ab .

Any of these forms can be used to display a fraction. A fraction is a division expression where both dividend and divisor are integers (although typically called the numerator and denominator). A fraction is an accepted way of writing numbers. It is not always expected that the result of the division is written in decimals.

A less common way to show division is to use the obelus (or division sign) in this manner:

<math>a \div b.</math>

But in elementary arithmetic this form is used rather often. The obelus is also used alone to represent the division operation itself, as for instance as a label on a key of a calculator.

In some non-English-speaking cultures, "a divided by b" is written a : b. However, in English usage the colon is restricted to expressing the related concept of ratios (with a:b said as "a is to b").

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