factors and multiples

• prime numbers


  a number that can only be divided by 1 and itself
• whole numbers


  any positive number that does not include a fractional or decimal part. they start from 0
• any whole number greater than 1 can be expressed as a product of two whole numbers
• 2 is the only even prime number because all even numbers are divisible by 2
• there are infinitely many prime numbers
• the opposite of prime numbers are composite numbers
• if a number is divisible by a composite number then it is divisible by all of the prime numbers which are factors of this composite number
• to check if a number is a prime number, check if it is divisible by any prime number smaller than itself. if it is it is not a prime number
• index notation


  a number multiplied by itself can be written with a small number on top to show how many times it has been multiplied by itself
• HCF


  highest common factor
• finding HCF


  find the common factors and multiply them
• LCM


  lowest common multiple
• finding LCM


  find the factors then only take into account the numbers repeated once and multiply
• square and cube roots


  theyre just duplicates of the same equation