Explain why 5 is a prime number. 02.11.17 LI: To recall prime numbers to 19 and to identify a method for finding prime numbers to 100. Success Criteria: To know what a prime number is To understand what a composite number is. To confidently recall all prime numbers to 19 and have methods for working out prime numbers past 19 Explain why 5 is a prime number. 5 Compare your answer with a partner. What improvements can be made to your explanation? 5 is a prime number because the only factors are 1 and 5, 1 and the number itself. (5 is not a multiple of 2, 3 or 4. It is only a multiple of 1 and 5, 1 and itself.)

Fluency

Fluency

Reasoning and problem solving To find a prime number to 100 you need to follow this simple rule. You can either do 6n + 1 or 6n – 1 Sometimes you can do both. Try it!!! Prove it!!! Does it work?

Reasoning and problem solving

Reasoning and problem solving with greater depth What happens if you go past 100. Could you identify if 281 and 283 are prime numbers? Would that be easy? Try this: Add the numbers together to find the digital root 2 + 8 + 1 = And 2 + 8 + 3 = Can you divide the answer 3? If you can, then it is not a prime number. What happens if you can’t