© B. Taylor - 2004

Natural Numbers
The counting numbers
1, 2, 3, 4, 5, . . .
Integers
Include all the whole
numbes and zero
. . . -3, -2, -1, 0, 1, 2, 3, . . .
Rational Numbers
Include all the integers
plus fractions
Real Numbers
Include all the Rational
Numbers plus numbers
that cannot be written as
fractions
N
Z
Q
R

Factor
A factor of a number divides
exactly into that number
eg: Factors of 14 are:
1, 2, 7 and 14
Prime Number
A number with exactly
TWO factors: (1 and itself)
2, 3, 5, 7, 11, 13, 17, . . .
Prime Factor
A factor of a number which
is also a prime number is
called a prime factor

Prime Factor
A factor of a number which
is also a prime number is
called a prime factor

eg 1: Write 24 as a product of Prime Factors
Prime Factor
A factor of a number which
is also a prime number is
called a prime factor
24
÷ 2
12
÷ 2
6
÷ 2
3
÷ 3
1
24 = 2 x 2 x 2 x 3
= 2 x 33
Keep dividing by
prime numbers
until you get to an
answer of 1

REAL NUMBERS
Rational Numbers Irrational Numbers
These include all the
whole numbers and
numbers which can be
written as a fraction.
ALL decimals which
recur or terminate can
be written as fractions.
These are all the and
numbers which can
NOT be written as a
fraction.
Examples:
pi
Square roots of primes
and multiples of primes.

Writing a terminating decimal as a fraction
(1) Write all the digits after the decimal point
(2) Draw a line under these
(3) Put a 0 under each digit
(4) Put a 1 in front of the 0s
(5) Simplify if possible
Examples
0.37
37
001
= 0.213
213
0001
= 0.013
013
0001
=
13
1000
=