Question

Which is the greatest 2-digit prime number?

Answer 1

Hint: We have this simple question. There is no big concept or formula implementing in this particular solution. If we know the definition of a prime number we can solve this easily. We can list out the two digit prime numbers and by observing the listed data we can say which is the greatest prime number.

Complete step-by-step answer:
Prime numbers are natural numbers greater than 1 that have only two factors. That is 1 and itself. Let’s list out the two digit prime numbers.
Since we have 2, 3, 5, and 7 as they are primes but we discard this because they are in single digit.
Now, the two digit primes are:
\[ 11,13,17,19,23,29,31,41,43,47,53,59,61,67,71,73,79,83,89,97 \]
We can see that all the above two digits numbers have only two factors, one is 1 and another is themselves.
Now, we can observe that the greatest two digit prime number is 97.
(We can solve this fast without listing the number. By means of checking backwards that is form 99. Since 99 and 98 are not prime numbers because both have more than 2 factors. So next we have 97 which is a prime number. Hence the answer is 97)
So, the correct answer is “97”.

Note: The greatest two digit natural number is 99. But 99 is not a prime number because it has factors 1, 3, and 9. If they ask what is the lowest two digit prime number. By observing the above listed number we can say that 11 is the lowest prime number (Although 10 is the two digit lowest natural number but it is not a prime number because 1, 2, and 5 are the factors of 10).