SAT Study Guide/Part 2 - The Math Section/General Numerical Concepts

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Number propertiesEdit

There are several sets of numbers:

  1. Counting or Natural numbers are numbers that can be used to count real things:  
  2. Integers (including 0) include the natural numbers and their opposites:  
    • Even integers are divisible by 2; you can express even integer as  , where   is any integer:  
    • Odd integers are not divisible by 2; you can express any odd integer as  , where   is any integer:  
  3. Rational numbers are numbers you can express as a fraction  , where   and   cannot simplify the other:  
  4. Irrational numbers are non-repeating, non-terminating decimals that you cannot express as a ratio or division of intergers  , where   and   cannot simplify the other:  
  5. Real numbers include all of the above.

Numbers can be prime. That is, they are divisible by themselves and one, only. 1 is not considered a prime number, and 2 is the only even prime number. The first eight prime numbers are: