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Types of Number
Prime Numbers
• Prime numbers are numbers that only
divide by themselves and 1
• 1 is not a prime number because it can
only be divided by 1
• 2 is the only even prime number
because all even numbers can be divided
by 1, 2 and themselves
• 5 is the only prime number that ends in 5
Prime Numbers
• 2,3,5,7,11,13,17,19,23,29,31,37,41,43
• Apart from 2 all the above numbers are
odd
• Apart from 5 they do not end in 5
• None of these numbers end in 0 (10, 20,
30 etc. can all be divided by 10)
• Apart from 2 and 5 all prime numbers end
in 1, 3, 7 or 9
Square numbers
• This is the sequence when numbers are
squared (2 dimensions)
• 1 x 1= 1, 2 x 2= 4, 3 x 3= 9, 4 x 4= 16, 5 x
5= 25, 6 x 6 = 36, 7 x 7= 49, 8 x 8 =64, 9 x
9= 81, 10 x 10 = 100
• You can find out if a number is a square
number by square rooting it, e.g.
• √144 = 12
Cube Numbers
• This is the sequence when numbers are
cubed (3 dimensions)
• 1 x 1 x 1= 1, 2 x 2 x 2= 8, 3 x 3 x 3= 27, 4
x 4 x 4= 64, 5 x 5 x 5= 125, 6 x 6 x 6= 216,
7 x 7 x 7= 343, 8 x 8 x 8= 512, 9 x 9 x 9=
729, 10 x 10 x 10= 1,000
• To cube a number on the calculator you
type in 2 Xy 3 (which equals 8)
• To find out if it is a cubed number you
would type 125 X1/y 3 (which equals 5)
Triangle Numbers
• These are the numbers you would need to
make triangles, starting with 1
• 1, 3, 6, 10, 15, 21, 28, 36, 45, 55
• 2 3 4 5 6 7 8 9 10
• The difference between triangle numbers
is easy to recognise
Questions
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What is the sequence of numbers: 36,49,64,81?
Square Numbers
What are the first five prime numbers?
2,3,5,7,11
Is 71 a prime number?
Find the square root of 71
It is 8
Does 71 divide by 2,3,5 or 7
No, so 71 is a prime number