Britain's Got Talent viewers fear David Walliams may have accidentally leaked his bank details on the show.
Damien O’Brien, 34 from London performed a magic trick involving his phone calculator.
He asked judges Simon Cowell, Alesha Dixon and Amanda Holden to each reveal a special date.
For Simon, it was February 14 - the day his son Eric was born.
Amanda answered December 10 - the day she married her husband.
And Alesha said October 1 - the day her daughter was born.
Damien then asked David to use his iPhone calculator to multiply those dates together, so 1,402 multiplied by 1,012, multiplied by 110.
The magician then told David to divide the number by his four digit banking pin code, which gave a total of 71,059.
David then proceeded to give Damien his credit card, which was placed physically through the phone.
Simon was then asked to take hold of the phone which magically had turned into a block of metal, engraved with the number 71059.
This number also happened to be the date Simon was born - October 7 1959.
Whilst many fans were blown away by the magic, others were concerned that David had given too many personal details away.
Zoe tweeted: "I hope that @davidwalliams has changed his pin code since the filming of #BGT."
Hannah said: "Sooo basically the whole of the UK now know David Walliams bank card pin."
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Another tweeted: "@davidwalliams you might want to change your PIN number now because quite a lot of people have worked it out."
And Ellie wrote: "Does this man know how maths works? Anybody with a brain cell can work out David’s pin code."
