Well I seem to have solved the print problem with print 'crt solution =', $crt1 -> bdstr(),"\n";

You can just as well use print $crt1, "\n"; or say $crt1;.
But printf "%.0f\n", $crt1; will simply round the value 954846259588805228035541587771 to a double:

use warnings;
use strict;
use Math::BigFloat;
use feature ':5.10';

my $x = Math::BigFloat->new('954846259588805228035541587771');

print $x->bdstr(), "\n";
print $x, "\n";
say $x;

printf "%.0f\n", $x;
printf "%.29e\n", 954846259588805228035541587771;

__END__

Outputs:

954846259588805228035541587771
954846259588805228035541587771
954846259588805228035541587771
954846259588805282215996948480
9.54846259588805282215996948480e+29
[download]

You get the correct output using "print" and "say" owing to operator overloading, and because $crt1 is a Math::BigFloat object.
Similarly, it doesn't matter whether you multiply/divide/add/subtract $crt1 with an integer, a perl floating point value, another Math::BigFloat object, or even a string.
This, again, can be attributed to operator overloading:

use warnings;
use strict;
use Math::BigFloat;
use feature ':5.10';

my $x = Math::BigFloat->new('954846259588805228035541587771');

print $x * 2, "\n";
print $x * 2.5, "\n";
print $x * Math::BigFloat->new('2.5'), "\n";
print $x * "2.5";

__END__

Outputs:

1909692519177610456071083175542
2387115648972013070088853969427.5
2387115648972013070088853969427.5
2387115648972013070088853969427.5
[download]

Cheers,
Rob