Wednesday, October 29, 2008
Tuesday, October 7, 2008
factors and greatest common factors
VOCABULARY
factors= If a number is a factor of another number it is divisible by it.
FACTORS To find out a numbers factors you need to know divisibility rules. Divisibility rules are like a short cut to finding out if a number is divisible by it or not. The number your trying to find the factors of and one are always one of the factors. To find out if a number is a factor of another number you you divide the number by the factor.
DIVISIBILITY RULES
2= if it's even 3= if the sum of the digits divisible by 3 5= if it ends in 0 or 5 6= if it is divisible by 2 and 3 9= if the sum of the digits is divisible by 9 10= if it ends in 0 11= if the 2 outside numbers add to give the middle number
EXAMPLE
multiples of 50=1,50,2,25,5,10,
GREATEST COMMON FACTOR
To find the greatest common factor (gcf) of too numbers you need to know the factors of both of the numbers (when you are first learning it then there are short cut ways). Then you find all the factors they have in common. After you know all the factors they have in common you pick the highest. Then you have the greatest common factor (gcf).
EXAMPLE
multiples of 50=1,50,2,25,5,10
multiples of 80=1,80,2,40,4,20,5,168,10
http://http://www.math.com/school/subject1/lessons/S1U3L1GL.html
factors= If a number is a factor of another number it is divisible by it.
FACTORS To find out a numbers factors you need to know divisibility rules. Divisibility rules are like a short cut to finding out if a number is divisible by it or not. The number your trying to find the factors of and one are always one of the factors. To find out if a number is a factor of another number you you divide the number by the factor.
DIVISIBILITY RULES
2= if it's even 3= if the sum of the digits divisible by 3 5= if it ends in 0 or 5 6= if it is divisible by 2 and 3 9= if the sum of the digits is divisible by 9 10= if it ends in 0 11= if the 2 outside numbers add to give the middle number
EXAMPLE
multiples of 50=1,50,2,25,5,10,
GREATEST COMMON FACTOR
To find the greatest common factor (gcf) of too numbers you need to know the factors of both of the numbers (when you are first learning it then there are short cut ways). Then you find all the factors they have in common. After you know all the factors they have in common you pick the highest. Then you have the greatest common factor (gcf).
EXAMPLE
multiples of 50=1,50,2,25,5,10
multiples of 80=1,80,2,40,4,20,5,168,10
http://http://www.math.com/school/subject1/lessons/S1U3L1GL.html
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