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Question
Which of the following is a prime number?
Options
81
87
91
97
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Solution
97
81 is not a prime number because 81 can be written as 9×9.
87 is not a prime number because 87 can be written as 29×3.
91 is not a prime number because 91 can be written as 13×7.
97 is a prime number.
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