Transcription of Worksheet b&tS100 Teacher Student Class
1 1234567891011121314151617181920212223242 5262728293031323334353637383940414243444 5464748495051525354555657585960616263646 5666768697071727374757677787980818283848 58687888990919293949596979899100 Sieve gives you a method for finding prime Cross 1 Then starting from 2, circle 2 but cross out every multiple of 2 from your Starting with 3, circle 3, but cross out every multiple of 3 from your Starting with 5, circle 5, but cross out every multiple of 5 from your Starting with 7, circle 7 but cross out every multiple of Do the same with all the primes that you know already. The numbers that are crossedare not primes, because they are multiples of other numbers. The numbers that arecircled are primes. They should have no divisors apart from themselves and Make a list of your primes.
2 Eratosthenes Sieve prime numbers up to b&tS100 TeacherStudentClassInvestigationHow many prime numbers are less than 100? Twin primes are two primes that differ by 2. 3 and 5 are twin primes because they differ by2. Clearly, 7 and 11 are not twin primes because they differ by 4. Can you find any other twinprimes on your sieve? Symmetrical primes are those where their digits are reversed. For example 17 and 71 are bothprimes. However, 23 and 32 are not symmetrical primes. Can you tell why?From your list of prime numbers (or the Sieve of Eratosthenes), find other pairs like 17 and 71. Have a look at how many primes there are up to 10, 20, 30, 40 and so on until 100. Describewhat you notice. Maths is Good for You is a web site dedicated to the history of mathematics for secondary school age students .
3 Its creation has been enabled by the GatsbyCharitable Foundation UK. You may use the material freely for educational purposes, research and private study but may not, for profit or any other purpose,reproduce or transmit it in any other form or by any means, or store it in any retrieval system of any nature without the written consent of the author. Requestsshould be addressed by e-mail to Maths is Good for YouMaths is Good ForYou Snezana Lawrence 2005
