use strict;
use warnings;
use Math::MPFR qw(:mpfr);

my $x = Rmpfr_init2(328);
Rmpfr_set_d($x, 1.0, MPFR_RNDN);
$x /= 526;

print $x;

# Outputs:
# 1.901140684410646387832699619771863117870722433460076045627376425855513307984790874524714828897338403e-3
# which is the same as the figure you've provided