Let ab, a ≠ b, is a 2- digit prime number such that ba is also a prime number. The sum of all such numbers is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 418.
It is hit and trial question one needs to think the digits first then one can find the solution.
All possible digits are, (13, 31) (17, 71) (37, 73) (79, 97)
Required sum = 13 + 31 + 17 + 71 + 37 + 73 +79 + 97 = 418.