def. Mulp: multiply arbitrary precision numbers.
For arbitrary precision numbers, see: this post.
How to multiply such numbers (num1, num2)?
1. For each partial multiplication in num1:
2. Multiply it by whole num2, inserting resulting partial multiplications in num2 as neccessary to result list (number) num3.
3. Flatten structure by adding multiplicator (n) parts of partial multiplications with same power (m), removing unneccessary partial multiplications from list (number) num3.