Skip to content

A pair of prime puzzles

May 27, 2006 pm31 3:22 pm

1.  The difference between two prime numbers is 33 35.  What is their product?

2.  Can you create a 3-digit number such that the number and all other numbers formed by premutations of its digits, are prime?  (eg, 127 is prime, and 271 is prime, but 172, 217, 721, and 712 are not…)  How many such numbers are there?

Advertisements
9 Comments leave one →
  1. Myrtle permalink
    May 30, 2006 am31 4:13 am 4:13 am

    Hi JD, have you got an email address where you can be reached?

  2. May 30, 2006 am31 4:25 am 4:25 am

    jd2718 at gmail dot com.

    I just got a new computer (went over to mac) and can’t figure out why your page looks so different. Mosaic is fine – there’s a fine mosiac museum in Antakya, old Antioch, in the part of Turkey that descends the Mediterranean coast towards Lebanon and that was briefly independent as the Hatay Republic between the world wars, and looks nothing like the fictional desert Hatay Republic that shows up in Raiders of the Lost Ark – {inhale} (Turkey on the brain) – Mosaic is fine, but the side bars have disappeared and I can’t back navigate, and I am sure I dropped some math comments, maybe Peano stuff? in some older posts.

    I just checked – your site looks fine on the pc. I’ll figure out the mac mess

  3. May 30, 2006 pm31 8:50 pm 8:50 pm

    Difference of 33? The only way that can happen is if one’s even and one’s odd. The only even prime is 2, which would make the other one 35. Which isn’t prime. What am I missing?

  4. May 30, 2006 pm31 9:59 pm 9:59 pm

    Opps.
    You’re not missing a thing. I meant 29. Managed to count the wrong way from 31. Thanks for pointing that out.

  5. February 7, 2008 pm29 10:17 pm 10:17 pm

    Easy, if you specify that two digits can repeat (there are about four such numbers.) If they can’t then there is no answer.

    Note: might ask if one can “find” a number since they’ve all been “created” for some time now.

  6. February 9, 2008 pm29 9:23 pm 9:23 pm

    Yes, and hmm.

    I can write “To be or not to be…” Now, if I claimed to be the first…

    Likewise, I can create a number. But I cannot claim that it is a new creation. (I know, I know, I am on shaky ground here).

    Was it Dedekind who said: “God created the naturals, all else is man’s creation”?

  7. February 9, 2008 pm29 9:23 pm 9:23 pm

    Correction:

    German mathematician Leopold Kronecker (1823–1891) is reported to have said, “God created the natural numbers; all the rest is the work of man.”

  8. February 10, 2008 am29 3:59 am 3:59 am

    You may not be able to create a number, but you can patent one!

Trackbacks

  1. JD2718 » Leftovers

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: