__M__

**Mass**
The measure of the amount of matter an object contains.

**Mean
** The value found by dividing the sum of a group of
numbers by the number of numbers in the group.
Also *called average.*

**Means
of a proportion ** The
second and third terms of a proportion.

**Measure
of central tendency **A number used to represent all the numbers in a set of
data. Three such measures are the mean, the median, and the mode

**Median
** The number that falls in the middle when data are listed
from least to greatest. If the
number of data is even, the median is the mean of the two middle

**Meter **The
unit of measure for length in the metric system

**Metric system **A system of measures based on powers of ten

**Midpoint ** The
point of a segment that divides it into two congruent segments.

**Mixed number ** A
whole number plus a proper fraction.

**Mode ** The number
that occurs most often in a set of data.

**Multiple
**A multiple of a whole number is the product of that number and any whole
number

**Multiplicand
**The second factor in a multiplication problem

**Multiplicative
inverse **Two numbers are said to be multiplicative inverses of each other if
their product is one

**Multiplier
**The first factor in a multiplication problem

*n
, n*¸1
*= *n

n,
*0* x *n= n* x 0*=*0

*n,
n + *0 =0 *+ n
*

*n,*1*
*x* n = n *x* *1 *= n
*