Question & Answer

What is the least prime number?

ANSWER Verified Verified
Hint: Definition of prime number is given as the number which has only two factors i.e. ‘1’ and the number itself and prime numbers are greater than 1. Use this property and definition of a prime number to get the least prime number. Don’t think that any even number cannot be a prime or any odd number will always be a prime.

Complete step-by-step answer:
We know that a prime number is a natural number greater than 1 that is not a product of two smaller natural numbers, where natural numbers in mathematics are those which are used for counting and ordering i.e. 1, 2, 3, 4 ………..
So, in other words, we can define a prime number as, a number that is divisible only by itself and 1 i.e. it will have only two factors ‘1’ and number itself.
So, let us check for the smallest prime number in mathematics. As we defined that prime number will be greater than 1, so, we need not to check ‘1’ whether it is prime or not. So, we should start verifying from the number ‘2’.
Hence, we get that there are only two factors of 2 i.e. ‘1’ and ‘2’, it means 2 has only two factors ‘1’ and the number itself.
So, by the definition of prime number that any number with two factors that is 1 and number itself, we get that ‘2’ is a prime number and least of them.
Hence, we get that the least prime number is ‘2’.

Note: One may go wrong if he/she will give answer ‘1’. As 1 is the least natural number and one may think that 1 is also a number not divisible by any other number and hence it can be a prime number; but it is wrong because we do not consider ‘1’ in the definition part of the prime as given in the solution, so, don’t confuse with it. ‘1’ is ignored for considering it as a prime number and we will not verify whether it is prime or not.
Now, one may give another answer as ‘3’ and ignore to check ‘2’ as prime as 2 is an even number. Because we know that any even number will have a factor i.e. ‘2’. So, one may think that 2 will not be a prime and give answer ‘3’ as ‘3’ has two factors ‘1’ and ‘3’. But it is wrong because 2 has also two factors ‘1’ and ‘2’ (number itself) so it will be a prime number as well from the definition of a prime number. And any other even number will not be a prime as 2 will be a factor of it. So, 2 is the least prime number (and even as well).