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Year Mathematics with Miss Hudson
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Whole Numbers, Integers, Counting Numbers!
The first numbers used are counting numbers {1, 2, 3, 4…} Then these with zero make up whole numbers {0, 1, 2, 3, 4…}. The whole numbers together with their opposites, -1, -2, -3…. make up the set of integers {… -3, -2, -1, 0, 1, 2, 3, 4…} Whole Numbers, Integers, Counting Numbers!
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Prime Numbers A prime number has exactly two factors, itself and 1.
2 is the smallest prime number, 1 is not a prime number. (After 2 , every other even number is not a prime!) Prime numbers are: {2, 3, 5, 7, 11, 13 ………..} By yourself list the next 6 Prime Numbers?
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Composite Numbers A Composite number is a natural number (positive integer) which is greater than 1 Has more than 2 factors. Example 1: The number 9 is a composite number because it has the factors of 1, 3 and 9. Example 2: 12 is a composite number because its factors are 1, 2, 3, 4, 6 and 12.
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It’s just like listing out your times tables
Multiples The multiples of a number are obtained by multiplying it by the natural (counting) numbers. example 1: The multiples of 10 are: 10, 20, 30, 40……… example 2: The multiples of 6 are: It’s just like listing out your times tables 6, 12, 18, 24, ………
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Note: The factors of a number always include 1 and itself.
The factors of a number are all the numbers that divide into it evenly with no remainders. e.g: The factors of 15 are {1, 3, 5, 15} Note: The factors of a number always include 1 and itself. Do you understand the difference between factors and multiples?
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Quick Quiz! Multiples of: 4 = 7 = 16 = 25 = 32 =
Factors of: 4 = 7 = 16 = 25 = 32 =
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Working left to right subtraction comes first
Order of Operations BIMDAS Brackets Indices Multiplication Division When both x and ÷ occur in a problem work from left to right. Addition Subtraction When both + and - occur in a question work from left to right Working left to right subtraction comes first examples: 1) 4 2) 3 x 4 4 _ 16 12
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Examples of BIMDAS cont’d
13 x 4 4) (2 x 32) + 4 ÷ 2 = 9 25 18 + 2 Work out the numerator first, the denominator second, and then do the division. 5) 2
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(subtraction was done before multiplication)
Order of Operations! It is very important to understand that it does make a difference if the order is not performed correctly!!!! 70 - 2x(5+3) = x(8) = 68 x (8) = 544 incorrect = x( 8) = = 54 correct (subtraction was done before multiplication)
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Factor trees & Product of Primes
E.g. Write 84 as a product of prime factors Start with ANY two numbers that multiply to give 84 84 We circle the prime numbers at the end of each branch. 2 42 2 21 3 7 Don’t forget to write the answer! 84 = 2 x 2 x 3 x 7 = 22 x 3 x 7
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Highest Common Factor (HCF)
The largest factor of two or more numbers! example: Find the HCF of 24 and 30 Method 1: The factors of 24 are: 1, 2, 3, 4, 6, 8, 12, 24 The factors of 30 are: 1, 2, 3, 5, 6, 10, 15, 30 The HCF of 24 and 30 is 6 Method 2: 2 3 HCF = 2 x 3 = 6
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Lowest Common Multiple(LCM)
The LCM of two numbers is the first multiple of each number that is the same. example: Find the LCM of 12 and 30 Method 1: Multiples of 12 are: 12, 24, 36, 48, 60, Multiples of 30 are: 30, 60, 90, 120…….. The LCM of 12 and 30 is 60 Method 2: 2 3 LCM = 2 x 3 x 2 x 5 = 60
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Index Notation/Integer Powers
4 x 4 x 4 x 4 x 4 = 45 2 x 2 x 5 x 5 x 5 = 22 x is read as “4 to the power of 5” Two special names are squared, e.g. 4 squared = 4 x 4 = 4 2 cubed, e.g. 2 cubed = 2 x 2 x 2 = 2 3 index/power/exponent base
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Powers on a calculator Calculators generally have for x squared
for x cubed for other powers To calculate 4 9 we would key in: and get the answer x 2 x 3 4 9 = Always enter negatives with brackets. (-3)2 = ( (-) 3 ) x 2 = 9
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1st Index Law: Multiplication
When multiplying terms with the same base we add the powers. Eg 1: y3 x y4 = y7 Eg 2: x = 28 Eg 3: 3 m2 x 2 m3 = 6 m5 Eg 4: c2d5 x 6c5d = 6 c7d6
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2nd Index Law: Division 98 ÷ 95 = = 93 9 x 9 x 9 x 9 x 9 x 9 x 9 x 9
So although it has a divide sign, when we are dividing indices we actually subtract them. However this can only be done when there is the same base!
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When dividing terms with the same base we subtract the powers.
eg 1: p 8 ÷ p 2 = p 6 5 5 x4 eg 2: 20x7 ÷ 4x3 1 2 m eg 3: or 3
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Square Numbers & Square Roots
If you multiply a number by itself you get a square number ie 1 x 1 = 1; 2 x 2 = 4; 3 x 3 = 9; 4 x 4 = 16 etc So 1, 4, 9, 16, 25, 36……. are square numbers The square root of 25 is 5, because 5 x 5 = 25 The symbol for square root is so On the calculator: 2 5 = It’s cool to be square
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Divisibility Tests A number is divisible by Rule 2
If it is even (ends in 0, 2, 4, 6 or 8) 3 If the sum of the digits is divisible by 3 4 If the number formed by the last 2 digits is divisible by 4 5 If it ends in 0 or 5 6 If it is divisible by 2 and 3 8 If the number formed by the last 3 digits is divisible by 8 9 If the sum of the digits is divisible by 9 10 If it ends in 0 12 If it is divisible by 3 and 4
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