Prime Numbers Demonstration This resource provides animated demonstrations

Prime Numbers – Demonstration This resource provides animated demonstrations of the mathematical method. Check animations and delete slides not needed for your class.

List the factors for each of these numbers. 16 7 4 11 9 13 25 14 1, 16, 2, 8, 4 1, 7 1, 2, 4 1, 11 1, 9, 3 1, 13 1, 25, 5 1, 14, 2, 7 How could we categorise these numbers according to their factors (put them into groups)? Numbers with two factors: Prime numbers Numbers with an odd amount of factors: Square numbers 7 11 13 16 4 9 25

A prime number is a number that has exactly 2 factors. 7 14 1, 7 1, 14, 2, 7 Prime Non-Prime numbers are the building blocks for all numbers because every number has at least one prime factor. Large prime numbers are very difficult to find, this makes them useful for encryption like in banking and online messaging.

For 1 to 50, how many prime numbers are there? Start at 1 and work up. Can you develop a method? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

How can we find prime numbers? Instead of finding prime numbers, we can do the reverse: eliminate non-prime numbers. We know multiples of 2 can’t be prime… so we can eliminate them (but not 2!) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

Prime numbers from 1 to 100 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 & 97

Questions? Comments? Suggestions? …or have you found a mistake!? Any feedback would be appreciated . Please feel free to email: tom@goteachmaths. co. uk