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LOS ANGELES (AP) - Benedict Cumberbatch is a star used to working with other stars, but even he was impressed by the cast of a new project.

The British actor of "Sherlock" and "Star Trek" fame appears with a pair of "Sesame Street" Muppets in a PBS video. It was posted Tuesday on PBS' YouTube channel.

With the help of Count von Count and Murray Monster, Cumberbatch explains how to count up four apples and three oranges, and which is the greater number.

He also tries to convince a stubborn Murray that he's not really Sherlock Holmes but just plays the detective on TV.

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