Brain Teasers
Sophie
Group
These brain teasers rely on your ability to recognize groups of common attributes. For each of these puzzles you'll need to figure out why the words or letters are grouped as they are. Sometimes you will be asked to pick the odd-one-out or to place a new word into the correct group.Group
Which number doesn't belong and why?
23, 41, 89, 11, 43, 131
23, 41, 89, 11, 43, 131
Hint
1. Notice they are all prime numbers.2. The title is a hint.
Answer
43 because the rest are Sophie Germain primes. Sophie Germain primes are prime numbers where if you multiply it by 2 and add 1, you still have a prime number.23*2+1=47
41*2+1=83
89*2+1=179
11*2+1=23
131*2+1=263
but
43*2+1=87
Hide Hint Show Hint Hide Answer Show Answer
What Next?
View a Similar 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.
Solve a Puzzle
Comments hidden to avoid spoilers.
Follow Braingle!