Which of these number does NOT belong to the group? A. 83 B. 91 C 71 D. 97

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Answer 1 · 2018-04-02T07:19:38

The correct answer is $B$ . See explanation.

Among the four numbers thare are 3 prime numbers. The only composite number (i.e. the number which is not prime) is $91$ .

A number greater than one is prime if it is only divisible by $1$ and itself.

Number $91$ is not prime because it can be written as:

$91=7*13$