Last week we finished up LCM and learned about GCF (Greatest Common Factor). Today we reviewed and we have a Unit test tomorrow, 9/18/17. Click **here** to open the review presentation we used in class. Your child should have other examples from today in their math notebook.
The LCM uses multiplication to find multiples. The GCF uses division to find factors. Again, knowing ones multiplication facts is the bedrock of these activities. Without that knowledge students will struggle a bit. They can skipcount, but it is less effective and more time consuing, and leaves more room for error. Factors - the two (or more) numbers we multiply together to get a new number (product). 2 and 3 are factors of 6 because 2 x 3 = 6. 1 and 6 are also factors of 6 because 1 x 6 = 6 as well. Greatest Common Factor (GCF) - This is the largest factor that is common to both of the original numbers given. Ex: Find the GCF of 8 nd 18. Step 1: List factors of both numbers 8 16 1 8 1 16 2 4 2 8 4 4 Step 2: Find the common factors. In this case those are 1, 2, 4, and 8. Step 3: Pick the greatest (largest) common factor from step 2. That would be 8. GCF = 8 Why is this important? Suppose you are throwing that Labor Day party and you want to provide treat bags for the 12 children attending. You bought 132 pieces of assorted candy and 24 candybars. To determine if you can create treat bags that are exactly the same, you can use GCF. 24 132 1 24 1 132 2 12 2 66 3 8 3 44 4 6 4 33 6 22 11 12 Here, the GCF is 12. That means you can create 12 treat bags that are identical from the candy and candy bars you bought. Each bag would get 2 candy bars and 11 pieces of candy. GCF practice: (Pick one or more) 1. IXL 2. Mathscore.com 3. Mathgames.com 4. Sheppardsoftware.com
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This week we will learn about multiples and least common multiples.
Students can best help themselves this week by studying and memorizing their multiplication facts (well, half of them anyway. They already know about "half"). Multiples - when we pick a number, like 4, and we multiply but another whole number, like 1, we get a multiple of 4. In this case, 4 x 1 = 4. The answer, 4, is the multiple. Ex: 4 x 2 = 8. 8 is a multiple of 4. We will also mention that 2 and 4 are the factors of 8. Least Common Multiple (LCM) - This is the smallest multiple, common to both/all of the orginal numbers we are given that they have in common. Ex: If we want to find the LCM of 4 and 6, we do the following. Step 1: List the first few multiples of 4: 4, 8, 12, 16, 20, 24, 28, 32 Step 2: List the first few multiples of 6: 6, 12, 18, 24, 30, 36, 42 Step 3: Look at each list and find the smallest number they have in common. In this case, it is 12. Even though they also share 24 and several other multiples, 12 is the LEAST COMMON multiple they share, so that is their answer. Why is this important? Suppose you are throwing a Labor Day party and need hot dogs. Hot dogs come in packages of 10, buns come in packages of 8. You can find the total number of packages that you need to buy to have an equal number of hot dogs and buns. Hot dogs (packs of 10): 10, 20, 30, 40, 50, 60, 70, 80 Buns (packs of 8): 8, 16, 24, 32, 40, 48, 56, 64, 72, 80 In order to buy an equal amount of hot dogs and buns, you should buy 4 packages of hot dogs and 5 packages of buns. LCM practice: (Pick one or more) 1) KhanAcademy 2) IXL 3) Mathgames 4) Sheppardsoftware |
core 3Archives
February 2018
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