Modulo the number found in the string by 26
decrypted_str += ' a ' + modulo_by_26 ( num_found_so_far ) ; num_found_so_far = " " ; } } if ( num_found_so_far . length ( ) > 0 ) { decrypted_str += ' a ' + modulo_by_26 ( num_found_so_far ) ; } return decrypted_str ; }