In your first block of code you do a calculation whose resulting denominator is more than 64 bits. So the result is a Num.

So what you're telling me is that it's "working as designed"? There seems to be no way to get exact rational calculations without scattering a bunch of explicit FatRat conversions through my code. If I slip up somewhere, Perl6 will either hit me with a sneaky type error, or (worse) silently reduce precision on me.

Your third block is an LTA error message.

Lighter Than Air? Lawn Tennis Association? Long-Term Abuse?