17 is aprime number. When the digits are

Question

reversed, the resultis 71, which is also a -
prime number. Findother examples of
prime numbers that produce a prime-
number when the digits are reversed.

Answer 1

To find prime numbers that produce a prime number when the digits are reversed, we can start by checking single-digit prime numbers (2, 3, 5, 7) and their reversed forms.

For the given example, 17, when the digits are reversed, we get 71, which is also a prime number.

Let's check other single-digit prime numbers:

1. When the digit 2 is reversed, we get 2 again, which is a prime number.
2. When the digit 3 is reversed, we get 3 again, which is a prime number.
3. When the digit 5 is reversed, we get 5 again, which is a prime number.
4. When the digit 7 is reversed, we get 7 again, which is a prime number.

So, all single-digit prime numbers and their reversals are prime numbers.

Let's continue checking two-digit prime numbers:

1. 11 is a two-digit prime number, but when its digits are reversed, we also get 11. However, 11 is not considered a prime number for this question since reversing the digits doesn't give a different prime number.
2. 13 is a two-digit prime number. When we reverse its digits, we get 31, which is also a prime number.
3. 17 (already checked) is a two-digit prime number. When we reverse its digits, we get 71, which is also a prime number.
4. 19 is a two-digit prime number. When we reverse its digits, we get 91, which is not a prime number.

Therefore, the examples of prime numbers that produce prime numbers when their digits are reversed are:

13 and 31
17 and 71