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Prime numbers and factors.

Prime numbers and factors. In this presentation I will be explaining prime numbers, how to find prime factors of numbers and the Highest conmen factor and the lowest conmen multiple. Prime numbers divide by themselves and one. So… 3=3*1…or… 13=13*1 But 16 divides 16*1 and 8*2 and 4*4

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Prime numbers and factors.

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  1. Prime numbers and factors. In this presentation I will be explaining prime numbers, how to find prime factors of numbers and the Highest conmen factor and the lowest conmen multiple.

  2. Prime numbers divide by themselves and one. So… 3=3*1…or… 13=13*1 But 16 divides 16*1 and 8*2 and 4*4 So you see that prime numbers are very specific. Just remember 2,3,5,7,11,17 Prime numbers

  3. Prime factors are factors of numbers like 108 that are prime. For example: the factors of 108 are 2,2,3,3,3 When you multiple all these numbers together you will get 108. Try it. Prime factors

  4. We can make it simple. Lets use a tree. If we put the number at the top… lets say 90. We then work out all the factor of 90. just watch! 90 2 2 Now we highlight the prime numbers. 45 How to work out the prime factors of numbers 5 9 5 3 3 3 3

  5. Now you try these. Get some paper and draw trees. 136 2*2*2*17 54 2*3*3*3 21 3*7 2*2*3*5 60 Your turn! 90 2*3*3*5

  6. The highest conmen factor is found by using a Venn diagram. A Venn diagrams looks like this. HCF (Highest conmen factor)

  7. You will be given two numbers that you will have to find the prime factors for. So find the prime factors for these two numbers. • 100 25 • Answers • 2*2*5*5 5*5 • Now look at the similar numbers. There are two fives in both the answers. So these go in the middle of the Venn diagram. You don’t repeat these numbers To work out the HCF you need to multiple all the numbers in the middle of the Venn diagram. So 5*5=25 The HCF =25 5 2 5 2 100 25

  8. If you get stuck click on the question mark at the top of the screen and watch the previous slide again. 54 HCF = 3 21 136 HCF= 4 60 Your turn

  9. To work out the LCM you do the same as the HCF but instead of multiplying the numbers in the middle of the Venn diagram you multiply all the numbers in the Venn diagram. 5 2*2*5*5=100 LCM=100 You will find that the LCM is always bigger than the HCF. 2 5 2 LCM (lowest conmen multiple 100 25

  10. If you get stuck click on the question mark at the top of the screen and watch the previous slide again. 54 LCM=378 21 LCM=2040 136 60 Your turn

  11. Well done. • Try the Homework on Mymaths.

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