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 So you see that prime numbers are very specific. Just remember 2,3,5,7,11,17

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.

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! Now we highlight the prime numbers

* Now you try these. Get some paper and draw trees *3*3*3 2*2*2*17 2*2*3*5 2*3*3*5 3*7

* The highest conmen factor is found by using a Venn diagram. A Venn diagrams looks like this.

* 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. * * Answers * 2*2*5*55*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

* If you get stuck click on the question mark at the top of the screen and watch the previous slide again HCF = 3HCF= 4

* 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 *2*5*5=100 LCM=100 You will find that the LCM is always bigger than the HCF.

* If you get stuck click on the question mark at the top of the screen and watch the previous slide again LCM=378LCM=2040

* Well done. * Try the Homework on Mymaths.