I made my project.
This doesnt use bignums.
Link: Snap! Build Your Own Blocks
Feel free to use!
I understand that you where attracted by the exponentiation and logarithms realtionship, but spot the difference 
This is actually "rounding".
Not really. It was just the precision loss.
The whole point of the Bignum library is to operate on numbers of arbitrary length with full precision.
Uhhhh......
I see! It's precision loss.