Thanks. I will try different approachs.

My code passed 279 tests and timed out at 1 test (may be the n = 2**42 test). @G_kuldeep, can you help?

Below are the results of different values of n that my code returned within max 5.0s. If the results are correct, then I don't understand why am I getting the timeout error.

10 = 5
100 = 21
1000 = 86
10000 = 356
100000 = 1479
1000000 = 6137
10000000 = 25474
100000000 = 105729
1000000000 = 438744
10000000000 = 1820598
100000000000 = 7554625
1000000000000 = 31347587
2**41 = 51015490

Is 51015490 the right answer for n = 2**41

Sorry. I am a beginner in the coding world. I had to figure out the markdown thing. Pls check the updated code block.

Being a beginner, it took me a lot time to solve this Kata. But finally I was able to solve this Kata and without using any external library. BUt had to hard code for '1001'.