Multiple (mathematics)

 ( Arithmetic ) 

In mathematics, a multiple is the product of any quantity and an integer. In other words, for the quantities a and b, it can be said that b is a multiple of a if b = na for some integer n, which is called the Multiplication. 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. If a and b are not integers, mathematicians prefer generally to use integer multiple instead of multiple, for clarification. In fact, multiple is used for other kinds of product; for example, a polynomial p is a multiple of another polynomial q if there exists third polynomial r such that p = qr.

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Examples 14, 49, −21 and 0 are multiples of 7, whereas 3 and −6 are not. This is because there are integers that 7 may be multiplied by to reach the values of 14, 49, 0 and −21, while there are no such integers for 3 and −6. Each of the products listed below, and in particular, the products for 3 and −6, is the only way that the relevant number can be written as a product of 7 and another real number:

$14\; =\; 7\; \backslash times\; 2;$

$49\; =\; 7\; \backslash times\; 7;$

$-21\; =\; 7\; \backslash times\; (-3);$

$0\; =\; 7\; \backslash times\; 0;$

$3\; =\; 7\; \backslash times\; (3/7),\; \backslash quad\; 3/7$ is not an integer;

$-6\; =\; 7\; \backslash times\; (-6/7),\; \backslash quad\; -6/7$ is not an integer.

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Properties

• 0 is a multiple of every number ($0=0\backslash cdot\; b$).
• The product of any integer $n$ and any integer is a multiple of $n$. In particular, $n$, which is equal to $n\; \backslash times\; 1$, is a multiple of $n$ (every integer is a multiple of itself), since 1 is an integer.
• If $a$ and $b$ are multiples of $x,$ then $a\; +\; b$ and $a\; -\; b$ are also multiples of $x$.

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Submultiple In some texts, " a is a submultiple of b" has the meaning of " a being a unit fraction of b" ( a b/ n) or, equivalently, " b being an integer multiple n of a" ( bn a). This terminology is also used with units of measurement (for example by the BIPM and NIST), where a unit submultiple is obtained by prefix the main unit, defined as the quotient of the main unit by an integer, mostly a power of 10³. For example, a millimetre is the 1000-fold submultiple of a metre.. Section 4.3: Decimal multiples and submultiples of SI units: SI prefixes. As another example, one inch may be considered as a 12-fold submultiple of a foot, or a 36-fold submultiple of a yard.

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See also

• Unit fraction
• Ideal (ring theory)
• Decimal and SI prefix
• Multiplier (linguistics)

Categories: Arithmetic, Multiplication, Integers

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