Hollywood actress Gwyneth Paltrow is amazed she landed the part of a mathematical genius in PROOF, because she was terrible at the subject in school.

The 33-year-old star, married to Coldplay frontman Chris Martin, finds it difficult to relate to her character CATHERINE in the JOHN MADDEN-directed movie because she continues to struggle with sums to this day.

She says, "I was terrible, on a retard level, at maths so it's very ironic that I'm playing a maths genius because I can hardly figure out what percentage to leave as a tip at the end of a meal."