Katy Perry and Justin Trudeau prove they are still going strong - and don't feel their ages - with a recent date night snap. "How old would you be if you didn't know how old you were?" Perry, 41, captioned a series of Instagram photos on Friday, March 27. The caption appeared to be tailored to Perry's first picture of the couple out to dinner. In the photo, Perry and Trudeau, 54, are both holding up their phones to show their "biological ages" after taking a quiz together. The "Roar" singer's result revealed that she is 33.