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Minimal Primes (Posted on 2012-04-24) Difficulty: 3 of 5
409 is an interesting prime number. If you remove any number of its digits, then you will get a number that is not prime.

0=not prime

Call a number with this property a minimal prime. Find all minimal primes.

No Solution Yet Submitted by Math Man    
Rating: 4.6667 (3 votes)

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re: solution | Comment 4 of 5 |
(In reply to solution by Charlie)

640009 is not a minimal prime. If you remove the 6 and two 0's, then you will have 409, which is prime. Also, you missed 946669 in your list.

  Posted by Math Man on 2012-04-24 17:26:45
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