Thank you very much. I solved my issue with adding and subtracting 1 from the returned value.
I think that perl should do this internally. 
my $l = log(125) / log(5);

$l += 1;
$l -= 1;

print $l == int($l);

[download]

Thank you all for the great answers.

In reply to Re^2: log() and int() problem by Anonymous Monk
in thread log() and int() problem by Anonymous Monk

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