1)
Any whole number can be expressed as a product of two or more factors.
Expressing a number in this way is called factoring. For
example:
A number that can ONLY be factored into 1 and itself is called prime.
A number that is not prime is called composite. The numbers
3, 7, and 11 are prime while 6, 12, and 32 are composite. The Fundamental
Theorem of Arithmetic says that every whole number can be factored
into a unique set of primes.
2) The real numbers contain the following sets of
numbers:
The natural numbers are the numbers 1, 2, 3,…
continuing on indefinitely.
ii) The integers are …, -3, -2, -1, 0, 1, 2, 3,…
iii) The rational numbers are the set of numbers of the
form a/b where a and b are integers.
iv) The irrational numbers are all real numbers that are
not rational. Examples include 
and
.
The decimal form of an irrational number goes on and on forever without
repeating or terminating.
3) To convert a fraction to a decimal divide the
numerator of the fraction by the denominator. All rational numbers will
yield a decimal that either terminates or repeats indefinitely. For
example:
To convert a decimal to a fraction remove the decimal
point from the number and make it the numerator of the fraction. The
denominator will be the power of ten corresponding to the last place value
of the decimal (0.1 is tenths, .01 is hundredths, ect.)
If the number has only zeros before and after the decimal point then
drop these zeros from the number in the numerator:
Fraction-Decimal Equivalents Worth Memorizing
