# Number Sets and Properties and measurements

unit 1+2 IB

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## Set langauge

• N* = counting numbers (1,2,3...)
• N= natural numbers (0,1,2,3,4)
• Z= intergers (0 +/-1 +/-2 +/-3)
• Z+ = positive intergers (1,2,3,4)
• Z- = negative intergers (-1,-2,-3)
• Q= rational numbers (can be written as a fraction)
• R= real numbers (all numbers on a number line)
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## intersection and union

• PC Q + =P is a subet of Q meaning that every element in P is also in Q
• P U Q= All the elements of P and Q together
• P ∩ Q= All the elements that are in both P and Q
• 2 E Q= 2 is an element of the set Q
• 2 E Q= 2 is not an element of the set Q
• { } or O= is an empty set containing no elements
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## Maths Words

• Terms- numbers
• product- result of a multiplacation
• Factors- Numbers which divide exactly into another number
• Quotient- The result of a division
• Divisor- the number by which we divide
• Dividend- the number being divided
• Sum= result of an addition
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## Primes and Composites

• Prime= a  natural number greater than 1 which has exactly 2 factors (itself and 1)
• Composite= a natural number greater than 1 which has more than 2 factors
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## BEDMAS

B= Brackets

E= E xponents (powers)

D= Division

M=Mulitiplacation

S= Subtraction

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## Error and Percentage Error

• Error= Estimated value- true value
• Absolute percentage error= (IerrorI/actual value)x 100% the error is used without the sign
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