Question

The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime. There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97. How many circular primes are there below 10000?write in c++

Answer 1

What is giving you problems?

Answer 2

rotation of numbers after getting prime numbers

Answer 3

int mod = prime % 10;
int divisor = prime / 10;

// could be replaced with a recursive function to find the power of ten to
// multiply mod by, but with only four possibilites......
if( divisor < 10 )
mod *= 10;
else if( divisor < 100 )
mod *= 100;
else if( divisor < 1000 )
mod *= 1000;
else
mod *= 10000;

divisor += mod;

// divisor is prime shifted right one digit
// not tested, try with a few and cout results