MATHS geniuses are again being invited to use their noodle to crack a code and win free food for the next six months.

Oxford's Wagamama restaurant has revived its competition 'due to popular demand'.

A code is being printed on placemats, windows and mirrors of the Market Street eatery until February 25.

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Anyone who can solve the puzzle is being invited to drop their answer into a ballot box and one entry will be selected at random to win the food.

Last year self-proclaimed riddle fanatics Klaudia Krawiecka and Vojtech Havlicek, both Oxford University academics, emerged as the winners.

The pair cracked the code over dinner using a technique called a five digit binary string.

Here's last year's riddle 

This year's challenge has been devised by Brian Tyrrell, a postgraduate student at Oxford University.

The winner will receive six months’ worth of wagamama food which will be awarded as a £500 e-gift card.