Is 87 a prime number?

1 Answer
Shwetank Mauria
Apr 2, 2016

#87# is not a prime number but is a composite number.

Explanation:

To check whether a number is a prime number or not, one may take a number less than approximately its square root.

Here a number less than approximately the square root of #87# is #9#, so one needs to try division of #87# by prime numbers up to number #9#.

As prime numbers up to #9# are only #{2,3,5,7}# and number is divisible by #3# (one can check by using divisibility rule),

#87# is not a prime number but is a composite number.

In fact #87=3xx29#

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