That of course is true Sensei - I had forgotten that it was I who had introduced the idea of the the leading zero.

I found that his Python code fails with f.e. num=30..

My .NET Framework version of it, is showing "30*1=44".

after using 64 bit integers I got:

30 * 143165578 = 4294967340

2^32 = 4294967296

4294967340 - 4294967296 = 44...

The most significant bit set, is truncated, because of overflow of 32 bit integer..

After using long long everywhere in code ends up in infinite loop (2^64 numbers to check).

Could you prove that for any integer n (not divisible by 10) there is a palindrome (in decimal representation) divisible by n?

Divisibility test for 11 is the answer you're searching for?

According to

https://en.wikipedia...lindromic_prime

"Except for 11, all palindromic primes have an odd number of digits,** because the divisibility test for 11 tells us that every palindromic number with an even number of digits is a multiple of 11**."

https://www.google.c...divisible by 11

Modified version of project. Instead of incrementing k by 1, it increments by 11.

**Palindrome.zip** **36.98KB**
3 downloads