Determining the GCF of 2 or More Numbers.pptx

Grade 5 Math

1. Determining the GCF of 2 or More N umbers. Kevin C. Secretario

2. Review: Give the prime factorization of: a . 18 = b . 27 = c . 24 =

3. Motivation: Tree different candies are to be put into candy bags so that the bags contain equal amounts of candies of the same kind. There are 180, 240 and 300 of the different kinds of candies respectively. Each candy has to get into a candy bag, that is, there must be no left over candies. How many candy bags that could be filled? How many candies will there be in a each bag? Can you think of a way of getting the answer to this problem? Let us analyze the problem. Since there should be no candies left over, the number of candies. This means that the number of candy bags must be a factor of 180, 240 and 300. Let us work with simpler numbers first.

4. Presentation a . Factor Lists A pupil will be asked to give a composite number less than 30, and give its factors. Another pupil will be asked to give another number with its factors.

5. Fixing Skills: Write the GCF of the following sets of numbers. a. 2 and 6 b . 5 and 20 c . 8 and 24 d . 8 and 56

6. Generalization What are the methods of finding GCF of given numbers? Which method do you like best? Why? Could these methods be used to find the GCF of 3 or more numbers ?

7. EVALUATION : Find the GCF of each set of numbers. 1.) 98 , 147 2.) 20 , 75 3.) 30 , 35 4.) 66 , 110 5.) 18 , 24, 54

8. ASSIGNMENT: Find the GCF of each set of numbers. 1.) 210 , 231 2.) 420 , 504 3.) 50 , 75, 100, 125 4.) 35 , 63 5.) 75 , 45

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