Find the $2$-digit prime numbers, in which both the digits are also prime numbers.

Finding the $2$-digit prime numbers, in which both the digits are also prime numbers:

The prime numbers are the numbers which is having only two factors that is one and itself.

The prime numbers are $2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97.$

In these prime numbers, both digits are also prime matches to the number $23,37,53$and $73.$

Hence, the $2$-digit prime number in which both the digits are also prime is $23,37,53$and $73.$