Brain Teasers
Which number doesn't belong?
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?
3
19
17
23
29
51
11
7
13
5
97
3
19
17
23
29
51
11
7
13
5
97
Hint
Remember your math.Answer
51 does not belong because it is the only number that is not prime.A prime number has only itself and 1 as factors. 51 has 4 factors: 1, 3, 17, and 51.
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