trulycrabby Posted August 16, 2014 Share Posted August 16, 2014 Hello, I might have found a mistake in the Primary Mathematics 5A Standards Textbook. Page 28, problem 13 states: "Find the sum of the prime numbers between 1 and 10. DS10 and I got 17: 2+3+5+7=17 The Teacher's Manual states the correct answer is 18, which is not possible unless 1 has suddenly become a prime number. Have I lost my mind? :o Quote Link to comment Share on other sites More sharing options...
nansk Posted August 16, 2014 Share Posted August 16, 2014 It appears to be a mistake. Quote Link to comment Share on other sites More sharing options...
IsabelC Posted August 16, 2014 Share Posted August 16, 2014 Looks like an error to me to. Didn't 1 used to be considered a prime years ago? Quote Link to comment Share on other sites More sharing options...
trulycrabby Posted August 16, 2014 Author Share Posted August 16, 2014 I don't know if 1 was ever considered prime. :o Thanks! I have to say I am not as crazy about this level/edition of Singapore math. Seems like I have found errors here and there, whereas I never found an error in the US Editions. Quote Link to comment Share on other sites More sharing options...
kiwik Posted August 16, 2014 Share Posted August 16, 2014 I'm pretty sure I was taught 1 was a prime number. A quick google search says that people my age were probably taught that 1 was a prime number. It seems to be a bit debated - like whether zero is odd or even. Quote Link to comment Share on other sites More sharing options...
trulycrabby Posted August 16, 2014 Author Share Posted August 16, 2014 I'm pretty sure I was taught 1 was a prime number. A quick google search says that people my age were probably taught that 1 was a prime number. It seems to be a bit debated - like whether zero is odd or even. I did some googling too, and understand that 1 used to be considered a prime number, but this edition of Singapore Math teaches that 1 is not prime. :ack2: Quote Link to comment Share on other sites More sharing options...
trulycrabby Posted August 16, 2014 Author Share Posted August 16, 2014 And then it says between 1 and 10. Would that include 1 and 10? KWIM? Yup, that bothers me too. Between 1 and 10 means greater than 1 and less than 10, so 1 shouldn't even be considered. Don't even get me started; their sections on Estimation and Approximation had my knickers in a twist. I am not very happy with this textbook, which is especially perplexing because I LOVED 4a and 4b US edition. I might even consider switching back to the US edition, because when comparing Standards and US edition, I like the US edition much better overall. Quote Link to comment Share on other sites More sharing options...
trulycrabby Posted August 16, 2014 Author Share Posted August 16, 2014 Ugh. Well I will keep this in mind. DS is currently working through 4a. Up until this point we used MIF. I decided to give this version a try. I mostly like it. Are you using Standards or U S edition? Quote Link to comment Share on other sites More sharing options...
kiana Posted August 16, 2014 Share Posted August 16, 2014 1 was sometimes classed as a prime a while ago. There's a discussion as to why it no longer is here: http://mathworld.wolfram.com/PrimeNumber.html -- note that some of the publication dates in works that have classed it as a prime reflect more recent reprints of classic texts, such as Hardy and Wright. As a side note about the parity of 0, it is an even number. There's a REALLY interesting discussion about misconceptions involving the parity of 0 here -- http://en.wikipedia.org/wiki/Parity_of_zero#Education Quote Link to comment Share on other sites More sharing options...
trulycrabby Posted August 16, 2014 Author Share Posted August 16, 2014 1 was sometimes classed as a prime a while ago. There's a discussion as to why it no longer is here: http://mathworld.wolfram.com/PrimeNumber.html -- note that some of the publication dates in works that have classed it as a prime reflect more recent reprints of classic texts, such as Hardy and Wright. As a side note about the parity of 0, it is an even number. There's a REALLY interesting discussion about misconceptions involving the parity of 0 here -- http://en.wikipedia.org/wiki/Parity_of_zero#Education I am still out of likes, but thank you very much for these links! Mathworld: Wow, I am in heaven with this site! :) Quote Link to comment Share on other sites More sharing options...
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