Ashton Kutcher can't remember when he got married.

The ‘What Happens in Vegas’ actor, who tied the knot with Demi Moore on September 24 2005, admits he often forgets his wedding anniversary.

He said: "I'm not good with dates. It takes me 20 minutes to remember my anniversary.”

Ashton, whose production company Katalyst is bringing family game show ‘Opportunity Knocks’ to the small screen, also revealed his involvement in the series has made him question how much he knows about Demi and his three stepdaughters Rumer, Scout and Tallulah.

He explained: "I got into the process of thinking, ‘How well do you know your family?’. If somebody came and asked me what kind of perfume my wife wears every single day, could I tell you that answer?

"I started playing with that idea with my family and with my girls, birthdays and anniversaries. Just who is Tallulah's favorite band? We would play for two bucks at the dinner table and we all had a blast with it."

Ashton, who at 30 is 15 years younger than his wife, is confident Demi would be a natural if she appeared on the program because she has such a great memory.

He added to America’s OK! magazine: "She would be a genius. I think my wife would dominate this show."