Prime Numbers

Prime Numbers

Prime Numbers
1. A prime number is a number that has exactly 2 different factors; itself and 1
2. 1 is not a prime number
3. Testing for prime numbers
  1. 1. Find the square root of the number
    1. 2. Check whether the number is divisible by prime numbers up to the square root
      1. Eg. Is 307 a prime number?
        The square root of 307 = 17.5
        If 307 is not divisible by 2,3,5,7,11,13,17, then it is a prime number
Multiples
1. Numbers in the times table
  1. Eg. Multiples of 7 are 7,14,21,28,35,42...
Factors
1. The numbers that divide into a number
  1. Eg. the factors of 12 are 1,2,3,4,6,12 as 12 is divisible by all these numbers
    1. The easiest ways to find the factors of a number is to list them in pairs
      1. Eg. factors of 36: 1 and 36, 2 and 18...
Products of prime numbers
1. To find the product of prime factors of a number it is useful to draw a factor tree
  1. 36
    1. 4
      1. 2
      2. 2
    2. 9
      1. 3
      2. 3
        2 x 2 x 3 x 3
        This is the product of the prime factors of 36
Highest common factor and Lowest common multiple
1. Use a factor tree for all numbers
  1. Make a venn diagram. Label that circles with each number. Put the common prime factors in the section where both circles cross.
    1. To find the highest common factor multiply the numbers in the section where both circles cross.
    2. To find the lowest common multiple multiply all the numbers in the venn diagram

Resumen del Recurso

	Creado por nadia.rauf hace alrededor de 9 años