Riley embarrassed by 'Countdown' mistakes

Countdown newcomer Rachel Riley has admitted that she feels like an "idiot" after making mistakes in her first days of filming.

The 22-year-old Oxford graduate took over as the Channel 4 gameshow's numbers and letters girl in December following the departure of Carol Vorderman.

Reports later revealed that Riley had found some number puzzles difficult to solve when she filmed her first episodes.

"I did struggle with some of the sums, but when you're flying through them you're not going to get them all," Riley told Celebs On Sunday magazine. "Afterwards you look back and think: 'What an idiot'.

"But you don't know whether you can do it or not in the 30 seconds you have, so you have to just go for it. It was difficult following in the footsteps of Carol - she is brilliant."

Speaking about the other challenges she has faced, Riley added: "I didn't have any training in front of the cameras and I wasn't even in the school play, so it is all new to me."

Countdown's ratings have increased since Riley and new host Jeff Stelling first appeared on screen earlier this month.