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Old 2010-09-03, 13:41   #23
Mini-Geek
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Quote:
Originally Posted by 3.14159 View Post
How about 77? 49? (7 * 11 and 72)
While it's subjective, I'd say these are much easier to spot as composite than 91, since one is a multiple of 11, and the other is a square. 91, on the other hand, is 7 times a prime greater than 10 that doesn't produce a clearly-visible way to identify it (e.g. with 11 times a single digit both digits are the same, and with 3 you can see that the digits add to a multiple of 3, but to see 91=7*13 I'd have to break it as 70+21 and then see that 21 is a multiple of 7).

Last fiddled with by Mini-Geek on 2010-09-03 at 13:44
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Old 2010-09-03, 14:13   #24
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Quote:
Originally Posted by Mini-Geek View Post
While it's subjective, I'd say these are much easier to spot as composite than 91, since one is a multiple of 11, and the other is a square. 91, on the other hand, is 7 times a prime greater than 10 that doesn't produce a clearly-visible way to identify it (e.g. with 11 times a single digit both digits are the same, and with 3 you can see that the digits add to a multiple of 3, but to see 91=7*13 I'd have to break it as 70+21 and then see that 21 is a multiple of 7).
As much as I hate to enter a conversation in which pi-man and science_man
are participating, I do have something material to add here.

Look up the paper by Selfridge et.al. entitled "Primes at a Glance"
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Old 2010-09-03, 17:31   #25
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Quote:
Originally Posted by R.D. Silverman View Post
As much as I hate to enter a conversation in which pi-man and science_man
are participating, I do have something material to add here.

Look up the paper by Selfridge et.al. entitled "Primes at a Glance"
As much as I hate to enter a conversation in which math-man is
participating, will he agree that the first uninteresting number is
greater than 91?

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Old 2010-09-03, 17:55   #26
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Please be kind.

R. D. Silverman's recommendation is excellent. I might also mention the Agoh-Erdős-Granville followup paper "Primes at a (somewhat lengthy) glance", probably one of the last papers Erdős wrote.
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Old 2010-09-04, 00:01   #27
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Quote:
Originally Posted by CRGreathouse View Post
Please be kind.
Hmm.

I thought quoting the great man verbatim was cutting
but appropriate and witty. If he is that thin-skinned, he should
moderate his own tone. I was merely attempting to console the
targets of his original jibe.

I'm sure his and your recommendations are valuable, enjoyable
and maybe even readable

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Old 2010-09-04, 02:10   #28
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Quote:
Originally Posted by Charles
Please be kind.

R. D. Silverman's recommendation is excellent. I might also mention the Agoh-Erdős-Granville followup paper "Primes at a (somewhat lengthy) glance", probably one of the last papers Erdős wrote.
I'm never going to be kind to low-down internet narcissists who pretends to know everything. Never will.

Quote:
Originally Posted by David
I thought quoting the great man verbatim was cutting
but appropriate and witty. If he is that thin-skinned, he should
moderate his own tone. I was merely attempting to console the
targets of his original jibe.
Expecting moderation from a narcissist is expecting the moon to be made of cheese.

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Old 2010-09-04, 04:21   #29
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Quote:
Originally Posted by davieddy View Post
I'm sure his and your recommendations are valuable, enjoyable
and maybe even readable
Eminently readable, actually! Possibly even by an undergraduate.
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Old 2010-09-04, 04:53   #30
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Quote:
Originally Posted by Charles
Eminently readable, actually! Possibly even by an undergraduate.
Excellent.

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Old 2010-09-04, 13:21   #31
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Quote:
Originally Posted by CRGreathouse View Post
Eminently readable, actually! Possibly even by an undergraduate.
What about a senile half-blind alcoholic?

David
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Old 2010-09-04, 13:26   #32
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Quote:
Originally Posted by 3.14159 View Post
I'm never going to be kind to low-down internet narcissists who pretends to know everything. Never will.

Expecting moderation from a narcissist is expecting the moon to be made of cheese.
Narcissus is a bit archaic.
I believe the current parlance is "head up one's arse".

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Old 2010-09-04, 14:12   #33
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Quote:
Originally Posted by David
What about a senile half-blind alcoholic?
Depends on whether or not he is intoxicated.
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