Show that 21 is not a prime number.

3 years ago

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Jayce Koch

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2 Answers

Jowella R Verified Sherpa Tutor ✓

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A prime number has only two factors i.e 1 and the number itself

Factors of 21 are 1,3,7,21

So 21 have more than 2 factors and that does not satisfy the condition of a prime number.

Hence 21 is not prime

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Richard A Verified Sherpa Tutor ✓

Primary Teacher with 15 years teaching experience. 11+ tuition.

For a number to be classified as a primary number it should have two factors. 21 has more than two factors i.e. 1, 3, 7, 21! So it is not prime!

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