First solve the problem at https://codingbat.com/prob/p202587 and then come to the current problem. Define a function that when passed an integer, returns true if it can be split in a way that the left and right parts are both prime, false otherwise. For example, you can split 7313 right down the middle and the left part - 73, and the right part 13, are both primes. BTW, you can also split it after the 7 so that both 7 and 313 are prime. Similarly, 893 split after the 9 results in primes on either side - 89 and 3. However, 277 cannot be split in a way that the left and right parts are prime.