return $bc unless length $base;
my $exponent = index ' kmgt', lc($2);
return $bc if ($exponent < 0 && $2);
$exponent = 0 if ($exponent < 0);
return $bc unless length $base;
my $exponent = index ' kmgt', lc($2);
return $bc if ($exponent < 0 && $2);
$exponent = 0 if ($exponent < 0);