Wonderlic Mathematics Review: Numbers and their Classifications

Numbers are the basic building blocks of mathematics.  Specific features of numbers are identified by the following terms:

Integers – The set of whole positive and negative numbers, including zero. 

Integers do not include fractions , decimals (0.56), or mixed numbers .
 

Prime number – A whole number greater than 1 that has only two factors, itself and 1; that is, a number that can be divided evenly only by 1 and itself.
 

Composite number – A whole number greater than 1 that has more than two different factors; in other words, any whole number that is not a prime number.  For example:  The composite number 8 has the factors of 1, 2, 4, and 8.
 

Even number – Any integer that can be divided by 2 without leaving a remainder.  For example:  2, 4, 6, 8, and so on.
 

Odd number – Any integer that cannot be divided evenly by 2.  For example:  3, 5, 7, 9, and so on.
 

Decimal number – a number that uses a decimal point to show the part of the number that is less than one.  Example: 1.234.
 

Decimal point – a symbol used to separate the ones place from the tenths place in decimals or dollars from cents in currency.
 

Decimal place – the position of a number to the right of the decimal point.  In the decimal 0.123, the 1 is in the first place to the right of the decimal point, indicating tenths; the 2 is in the second place, indicating hundredths; and the 3 is in the third place, indicating thousandths.
The decimal, or base 10, system is a number system that uses ten different digits ().  An example of a number system that uses something other than ten digits is the binary, or base 2, number system, used by computers, which uses only the numbers 0 and 1.  It is thought that the decimal system originated because people had only their 10 fingers for counting.

Rational, irrational, and real numbers can be described as follows:
Rational numbers include all integers, decimals, and fractions. 

Any terminating or repeating decimal number is a rational number.

Irrational numbers cannot be written as fractions or decimals because the number of decimal places is infinite and there is no recurring pattern of digits within the number.  For example, pi (π) begins with 3.141592 and continues without terminating or repeating, so pi is an irrational number.
 

Real numbers are the set of all rational and irrational numbers.