umsami Posted August 20, 2013 Share Posted August 20, 2013 If so why/why not? I seem to vaguely recall having to memorize them, but I can't for the life of me remember why. Was it a factoring thing? Quote Link to comment Share on other sites More sharing options...
kiana Posted August 20, 2013 Share Posted August 20, 2013 I guess it might have something to do with factorizing, but it honestly doesn't seem like something that's worth memorizing to me. As they practice factorizing, they should naturally start to remember which ones are prime and which ones are not. Quote Link to comment Share on other sites More sharing options...
NittanyJen Posted August 20, 2013 Share Posted August 20, 2013 We don't sit and memorize them . . . by the time you simply do enough problems with factoring, finding the LCM, GCF, finding square and cube roots by prime factorization, work through the sieve of Erastothanes a few times, they just start to recognize them. And if you aren't sure, you can pretty quickly test a number to see whether it's prime. You just kind of learn them through familiarity. Prime numbers are pretty darn useful, but since there are an infinite number of them, any place you'd like to cut off memorizing them would be necessarily quite arbitrary! Quote Link to comment Share on other sites More sharing options...
regentrude Posted August 20, 2013 Share Posted August 20, 2013 There is no need to memorize prime numbers. The student needs to memorize the times tables anyway; he will recognize the numbers that are NOT prime as products. All the numbers that are not among those are prime. Quote Link to comment Share on other sites More sharing options...
JoyceTWTM Posted August 20, 2013 Share Posted August 20, 2013 Prime Numbers--Do you have your kids memorize them? Yes, and also the Divisibility Rules http://images.tutorvista.com/cms/images/38/divisibility-rules-chart.jpg Quote Link to comment Share on other sites More sharing options...
quark Posted August 20, 2013 Share Posted August 20, 2013 One fun way we used was to ask questions like can you tell me the significance of the number 41? (ans: sum of first six prime numbers) and the same with divisibility rules. And we read living math/ murderous math type books. Games are also a good way to help remember imho. My son recommends: Prime Curios The Number Devil Quote Link to comment Share on other sites More sharing options...
lewelma Posted August 20, 2013 Share Posted August 20, 2013 My older son is just now beginning to memorize them because he is working towards the NZ Math Olympiad. A lot of problems at *that* level can have primes that need to be recongnized in order to uncover the proof. The quote by Pasteur applies here, "Chance favours the prepared mind." I will not be having my younger memorize them, as he is not interested in high-level math contests. Ruth in NZ Quote Link to comment Share on other sites More sharing options...
Luckymama Posted August 20, 2013 Share Posted August 20, 2013 Dd has "memorized" many, meaning she can recognize the primes, by working through problem after problem. In a similar way, she has "memorized" Pythagorean triples. As Ruth says, many contest problems hung on recognizing something key---a prime, a hidden right or equilateral triangle, etc. Quote Link to comment Share on other sites More sharing options...
NittanyJen Posted August 21, 2013 Share Posted August 21, 2013 "Chuck Norris knows all the prime numbers." (If you don't get it, google chuck Norris jokes) Quote Link to comment Share on other sites More sharing options...
NittanyJen Posted August 21, 2013 Share Posted August 21, 2013 "Chuck Norris knows all the prime numbers." (If you don't get it, google chuck Norris jokes) Quote Link to comment Share on other sites More sharing options...
serendipitous journey Posted August 21, 2013 Share Posted August 21, 2013 It's useful I suppose, but it seems highly unlikely to me that unless one is using it a lot that they will remember them. I don't find memorizing random lists of numbers to be useful. Wendy, I think this sums it up really! I'll be looking into the resources above (thanks, Quark!) but I think that if a child would benefit from memorizing them it will become clear. If she is interested in competitive maths, like Ruth's child; or a cryptography fiend perhaps. If you were required to memorize them, OP, you had a better maths education than I did! but the prime-memorization requirement seems more of an ornament (perhaps an annoying doodad; perhaps a lovely but unnecessary decoration) than an essential element of that education. Quote Link to comment Share on other sites More sharing options...
Down_the_Rabbit_Hole Posted August 21, 2013 Share Posted August 21, 2013 Nope. Usually when it is first mentioned in the curriculum each year I have them make a 100 chart on graph paper, then find the primes (circled in red). This paper is then kept for them to refer to if needed. By high school they usually have it memorized just from use. Quote Link to comment Share on other sites More sharing options...
Violet Crown Posted August 21, 2013 Share Posted August 21, 2013 So far, just learning of the existence of Buzz Rounds has sufficed to prompt the memorization of primes for my girls. http://www.artofproblemsolving.com/blog/5775 You can't win if you think 97 is prime! Chanting primes is also useful for the anxious when being given shots. But, on regentrude's side here, we don't require it; it just happens as you learn the math, and then gets extended as one of those household competitive show-offy things. Like memorizing squares, cubes, and digits of pi. Quote Link to comment Share on other sites More sharing options...
quark Posted August 21, 2013 Share Posted August 21, 2013 Chanting primes is also useful for the anxious when being given shots. But, on regentrude's side here, we don't require it; it just happens as you learn the math, and then gets extended as one of those household competitive show-offy things. Like memorizing squares, cubes, and digits of pi. There needs to be a love button for the bolded. :) I have a kid who does things like this too. :) We don't require it either and kiddo isn't into competitions of any sort (yet) but he has found his prime number trivia obsession to come in useful during math circle meetings. I don't think it's necessary to memorize it at all but if a child does it of his own free will, I'm not going to stop it either. :D Chalking it up as one of those fun things to know. Quote Link to comment Share on other sites More sharing options...
umsami Posted August 21, 2013 Author Share Posted August 21, 2013 Thanks everybody! :) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.