50 prime numbers

'Prime numbers upto 30' is not the same as 'upto 30th prime number.' Just saying.

Sent from my SM-G935F using GMAT Club Forum mobile app

Dear iMyself,

I'm happy to respond. I assume you acknowledge the mathematical mistakes in your original post.

1) What I said was that it was important memorize the prime numbers up to 30, that is, the set of prime numbers less than 30. This would be the very small set {2, 3, 5, 7, 11, 13, 17, 19, 23, 29}, which includes only 10 prime numbers. That is the list that I would say everyone taking the GMAT needs to know. Then I added, it might be helpful to memorize six more, all the prime numbers up to than 50, which would be the set {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47}, a set of 15 prime numbers. Not much more than that: certainly three-digit prime numbers are unnecessary.

2) My friend, you are a student. I am GMAT expert and I have explained thousands of GMAT math practice questions. In my wide experience, no official questions depend on having the 3-digit primes memorized. Such questions do not exist, but it's unclear how I would "prove" this absence to anyone. I would say that in a statement of absence, the burden of prove falls on the counterexample. For example, can you find a single official question, in the GMAT OG or from GMAT Prep, that actually depends on such knowledge? Such a question would prove me wrong: I would be quite intrigued to see such a question.

3) What I provided, not for GMAT knowledge, but purely for mathematical reference, was a list of "all the prime numbers up to 1000." As you may realize, 998, 999, and 1000 are not prime numbers, so the list of "all the prime numbers up to 1000" ends at 997. If a GMAT problem talks about prime numbers up to 20, you should understand what this means, the eight primes less than 20, and that the list of course doesn't include 20 itself.

Finally, my friend, I will caution you. The need to prove yourself right in this case has lead to misreadings of what I said, and it has the potential to mitigate against your ability to learn deeply in many instances. All true learning comes from a posture of humility and openness. Furthermore, the ability to admit mistakes demonstrates a person's maturity & security, and allows others to trust and respect him. Some unhealthy messages we get in life seem to suggest that being perfect and never wrong is the only way to get respect, but in fact, we get the most respect in life when we are profoundly comfortable and at peace with our own human fallibility. I am pointing all this out, my friend, precisely because I want to support your deep success as a student of the GMAT and in life.

Does all this make sense?
Mike

Hi everyone. I am so glad that I am a member in this forum. It is so interesting here.

I agree that is not necessary to remember too many prime numbers

Words that are very well said!

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.