To calculate the mean, median, mode, and range of a data set: The mean is found by adding all the numbers and dividing by the total; The median involves ordering the numbers and taking the middle value; The mode is the number that appears most frequently; And the range is the difference between the highest and lowest numbers. These statistical terms are used to summarize and analyze numerical data.

1. Mean, Median,
Mode, Range
Mean -
To find the
mean add all the numbers
together then divide the
answer by the amount of
numbers. Another name for
mean is average.
Median - To find the medium list all the numbers in
correct order, being sure to include an doubles. Then find the
middle number. If there is an odd amount of numbers - the
medium is the middle number. If there is an even amount the
medium is found by adding the middle two numbers together
and dividing by 2. The resulting number is the medium.
Mode - after listing all numbers in order, the mode is
that number which appears the most times. There can be
more than one mode provided they are listed the same
amount of times.
Range - is the distance
between the lowest and highest
number. It is found by
subtracting the lowest from the
highest.
Cite
http://www.numberpower.org/BeyondBasics/Data/HTML/Mean.html