Brain Teasers
Brain Teasers Trivia Mentalrobics Games Community
Personal Links
Submit a Teaser
Your Favorites
Your Watchlist
Browse Teasers
All

Cryptography
Group
Language
Letter-Equations
Logic
Logic-Grid
Math
Mystery
Optical-Illusions
Other
Probability
Rebus
Riddle
Science
Series
Situation
Trick
Trivia

Random
Daily Teasers
Search Teasers

Advanced Search
Add to Google Add to del.icio.us

More ways to get Braingle...

Prime Ponderings

Math brain teasers require computations to solve.

 

Puzzle ID:#19862
Fun:*** (2.71)
Difficulty:*** (2.78)
Category:Math
Submitted By:snaps*au****

 

 

 



What are the largest and smallest 5-digit numbers that satisfy the following conditions?

1. Each digit of the number is a prime digit.
2. Each successive pair of digits forms a 2-digit number that is NOT a prime number.
3. Each of the prime digits must appear at least once in the 5-digit number.

Open Calculator



What Next?

  
  

See another brain teaser just like this one...

Or, just get a random brain teaser

If you become a registered user you can vote on this brain teaser, keep track of
which ones you have seen, and even make your own.

 



Comments

jimrcook
Dec 16, 2004

Very nice one. I'd probably have solved it better if I hadn't misread criterion 3. I thought it said each must appear only once, and decided you must have counted 1 as a prime digit. There's no solution to that one. Sigh. Once I got over that, I saw the answer.
(user deleted)
Jan 02, 2005

Great puzzle. I enjoyed it.
cloud_strife**
Jan 19, 2005

"Of that list, 33 is the only number that contains a 3 as the second digit and so for criterion 3 to be satisfied, 3 can only appear at the start of the 5-digit numbers" hey, i don't get this part of the answer.. can u explain it more clearly? thanks
brianz**
May 11, 2005

Good one. Very fun.
solidtanker*
Jun 24, 2005

Enjoyable. I love prime numbers, they are a great mystery!
SunroseAus*
Sep 11, 2005

I enjoyed this math teaser
Good Job
javaguru*us*
Jan 28, 2009

It was easier to list the numbers that can,t be formed (23, 37, 53, 73) than the ones that can. This made the requirement of starting with a 3 clear and the rest was easy.

spikethru4*au*
Feb 10, 2011

@jimrcook - I made the same mistake, but if you include 1 as a 'prime digit' the smallest is 32157 and the largest 35721.
eddandi
Feb 16, 2011

1 is a prime number and is not included in this. why?
javaguru*us*
Mar 09, 2011

By definition, 1 is not a prime number.



Back to Top
   



Users in Chat : None 

Online Now: 16 users and 525 guests

Copyright © 1999-2014 | Updates | FAQ | RSS | Widgets | Links | Green | Subscribe | Contact | Privacy | Conditions | Advertise

Custom Search





Sign In A Create a free account