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The number of primes between 10 and 50 that remain primes when their digits are reversed is 

The number of primes between 10 and 50 that remain primes when their digits are reversed is  Correct Answer 5

Concept used:

Prime number:- A number that can be divided exactly only by itself and 1, for example, 2, 3, 5 etc

2 is only even prime number 

3 is the smallest odd prime number

Calculation:

Prime numbers between 10 and 50 are : 11 , 13 , 17 , 19 , 23 , 29 , 31 , 37 , 41 , 43 , 47

Reversing digits of prime numbers : 11, 31, 71, 91, 32, 92, 13, 73, 14, 34, 74

Still prime numbers : 11, 31, 71, 13, 73

Thus 5 numbers are still prime.

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