say is not the way to debug in perl6 as it is in perl5, and Num values are native in perl6, so Math::Float128 is a module that is nut useful to link to perl6 with Inline::Perl5:

$ perl6 -e'my $f = 1.2345; $f.say; $f.perl.say; $f.gist.say; $f.nude.say; dd $f'
1.2345
1.2345
1.2345
(2469 2000)
Rat $f = 1.2345
$ perl6 -e'my $f = 1 / 3.33; $f.say; $f.perl.say; $f.gist.say; $f.nude.say; dd $f'
0.300300
<100/333>
0.300300
(100 333)
Rat $f = <100/333>
$ perl6 -e'say π ** 25'
2683779414317.76
$ perl6 -e'.say for π ** 259'
5.77852541576782e+128