Questions tagged [primes]
A puzzle that involves and requires knowledge of prime numbers. Use with [mathematics]
11
questions
47
votes
5answers
4k views
Prime Number Snake
Place numbers 1 to 100 in the cells of the 10 x 10 board below in such a way that consecutive numbers occupy neighboring cells (either horizontally or vertically). Shaded cells should contain only ...
asked Jan 24 '20 at 2:28
Bernardo Recamán Santos
13.9k2 gold badges23 silver badges129 bronze badges
16
votes
3answers
3k views
Prime to Prime: Get all first 25 Prime Numbers using up to 4 Primes
The first 25 Prime Numbers are
2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97
Using up to 4 prime numbers and the following mathematical operations, get all the 25 primes.
+ ...
4
votes
1answer
205 views
Follow the path of relation through the grid #7
There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
3
votes
1answer
148 views
Follow the path of relation through the grid #8
There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
13
votes
1answer
337 views
Prime to Prime Sequel
This question is inspired by the Prime to Prime puzzle.
The first 24 Prime Numbers are
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89
Using up to 4 prime ...
6
votes
2answers
568 views
The largest Thursday number
A Thursday number is a number 𝑁 where any three consecutive digits make a prime, and all such primes formed are distinct.
For example, 13739 is a Thursday number because 137, 373, and 739 are all ...
15
votes
5answers
991 views
Dividing the first 20 numbers into 3 lists
Place every number from 1 to 20 into one of three lists $P$, $Q$ or $O$, such that any number from $P$ added to any number from $Q$ gives a prime. What is the fewest number of elements that can be in $...
8
votes
1answer
179 views
My Eight Cousins
My eight cousins are all a different prime number of years old, and their average age is a whole number. Recently they all came to visit me and, as they left one by one, I noticed that at all times ...
asked Jan 26 '21 at 19:33
Bernardo Recamán Santos
13.9k2 gold badges23 silver badges129 bronze badges
6
votes
2answers
413 views
Primes in a Line
Place the first 20 primes (2 to 71) in a line so that the sum or difference (or both) of any two primes that find themselves next to each other is always a perfect square.
For which other values of N ...
asked May 14 '20 at 17:18
Bernardo Recamán Santos
13.9k2 gold badges23 silver badges129 bronze badges
6
votes
4answers
2k views
Smallest number containing the first 11 primes as sub-strings
113257 contains the first 6 primes as sub-strings when reading them from left to right:
2: 113257
3: 113257
5: 113257
7: 113257
11: 113257
13: 113257
What is the smallest number that contains ...
4
votes
3answers
556 views
Neighbouring numbers summing to a prime on a 3x3
Can you place distinct numbers from 0 to 9 on a 3x3 grid such that every pair of neighbouring (horizontally and vertically) numbers sum to a prime? Can you find multiple solutions? Note that the ...