You can prepend a q before the ( to make eval work correctly, i.e. report the difference. 
$premium = eval q($number * ( 1 + 10/100 ));

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لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re^4: Results depending on evaluation order by choroba
in thread Results depending on evaluation order by fishy

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