Even integers can be divided by two without a remainder. The

even integers include 0, 2, 4, 6, 8, 10, 12, . . . , 2753

with −2, −4, −6, . . . , −37954, . . . Odd integers can not be divided by two without a remainder.

The odd integers include 1, 3, 5, 7, 9, 11, . . . , 2452 + 1, . . .

along with −1, −3, −5, . . . , −37955, . . . The median of a group of numbers is the number in the middle

of the group after the group has been numerically sorted. For

example, the median of the numbers {9, 2, 4} is 4, since when

sorted, the numbers are {2, 4, 9}, and 4 is in the middle. For

groups with an even number of numbers, the median is the

average of the two middle numbers. For example, the median

of the numbers {1, 1, 2, 4, 4, 9} is (2 + 4)/2 = 3. The mode of a group of numbers is the number or numbers

which appear most often (there can be more than one mode

for a given group). For example, the mode of the group of

numbers {1, 2, 3, 3, 3, 4, 5, 6, 6, 6, 7, 8, 8} is both 3 and 6. A rational number is any number that can be written as a

fraction: a ratio of two integers. Rational numbers include

1/2, 3/4, 5 (since 5 = 5/1), 22/7, 1/3, and so on. These

numbers can always be written as a finite decimal or as an

infinite decimal that repeats. For example, 2/5 = 0.4, 7/11 =

0.6363, and 22/7 = 3.142857.Important rational numbers to know from memory as decimals are: 1/2 = 0.5, 1/3 = 0.33, 1/4 = 0.25, 1/5 = 0.2, 2/3 = 0.66,and 3/4 = 0.75. ;