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A prime such that its decimal period's length is shared with no other prime is called a unique prime (as defined by Yates in 1980). 3, 11, 37, and 101 are unique primes, since they are the only primes with periods one ( 1/3=.3333), two (1/11=.090909... ), three and four respectively.

List the first 15 unique primes, explaining how you obtained them.

Copying a list from OEIS does not qualify as a solution, getting information from any source is encouraged.

(No Solution Yet, 1 Comments) Submitted on 2017-11-24 by Ady TZIDON    


What digit is not included in the solution of the above alphametic?

(No Solution Yet, 1 Comments) Submitted on 2017-11-23 by Ady TZIDON    

Difficulty: 1 of 5 Way to go (in Riddles) Rating: 4.00
A mixture of 3/7 chicken, 2/3 cat, and 1/2 goat creates what?
(No Solution Yet, 2 Comments) Submitted on 2017-11-22 by Ady TZIDON    

The sum of the first N consecutive prime numbers is a zeroless pandigital. Find N and the corresponding 1-9 pandigital.
(No Solution Yet, 1 Comments) Submitted on 2017-11-21 by Ady TZIDON    

What starts with T, ends with T, and is full of T?
(No Solution Yet, 3 Comments) Submitted on 2017-11-20 by Ady TZIDON    

What is the answer to this alphametic?


(No Solution Yet, 0 Comments) Submitted on 2017-11-19 by Ady TZIDON    

There is a finite number of Ulam numbers n, such that n+1 is also an Ulam number.

List all such pairs.

(No Solution Yet, 1 Comments) Submitted on 2017-11-18 by Ady TZIDON    

List all Pythagorean triangles whose area utilizes
9 different digits.
(No Solution Yet, 7 Comments) Submitted on 2017-11-17 by Ady TZIDON    

Difficulty: 3 of 5 Where Did You Start? (in Just Math) Rating: 4.00
2015 pieces of stones are placed to form a circle. They are numbered with 1,2,3,4,...,2015 clockwise. Starting from somewhere, you remove a stone. Then going clockwise, you remove every other stone, one at a time. Finally, there is only stone left, and that stone is 2014. What was the first stone you removed?
(No Solution Yet, 3 Comments) Submitted on 2017-11-16 by chun    

The question

"What is the longest sentence in the world?"

triggers a variety of valid answers

Provide some (existing or your own).

(No Solution Yet, 5 Comments) Submitted on 2017-11-15 by Ady TZIDON    

Let a fun number be a positive integer of the form 4x+1. Then, the fun numbers are 1, 5, 9, 13, 17, 21, 25, 29, 33, 37... Let a fun prime be a fun number that is not divisible by any fun number other than 1 and itself. For example, 5 is a fun prime. Also, even though 9=3*3, 9 is a fun prime because 3 is not a fun number. Now, every fun number can be factored into fun primes. For example, 25=5*5. Find the first fun number with more than one fun prime factorization.
(No Solution Yet, 2 Comments) Submitted on 2017-11-14 by Math Man    

Difficulty: 3 of 5 Making a 10 (in Numbers) Rating: 3.00
ONE: When I'm with you I feel ten times 12345673 !
ZERO: Darling, without you I'm 5429056...

01 02 2387?

(No Solution Yet, 3 Comments) Submitted on 2017-11-13 by Ady TZIDON    


7845'3 9416435 ?
(No Solution Yet, 0 Comments) Submitted on 2017-11-12 by Ady TZIDON    

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