Here you can download the full source to the Liberty Software Foundation software: https://github.com/RickCHodgin/libsf
Along the right side is a download link for the ZIP file. This contains all LibSF software, including Visual FreePro.

And attached is a version that just contains Bignum. Examine frmTest.scx and the Click() event on each button to see usage. Examine the Init() event to see how values are initialized. And if you MODIFY CLASS bignum OF bignum.vcx you'll see its inner workings.

Please report any bugs if you'd like. Thank you.