Types of Number Prime Numbers Prime numbers are
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= 1, 2 x 2= 8, 3 x 3= 27, 4 x 4= 64, 5 x 5= 125, 6 x 6= 216, 7 x 7= 343, 8 x 8= 512, 9 x 9= 729, 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 X 1/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 • • • 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
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