While most of 2018 was relatively insignificant, we can all agree that The Greatest Showman was one of the greatest movies of the late 2010s. The musical was largely about the life of P.T. Barnum (played by Hugh Jackman) who starts one of the most popular shows, what would later become Ringling Bros. and Barnum & Bailey Circus, on the planet. And while all of the songs and dance numbers were undeniably mesmerizing, one of the greatest aspects of the film was Zac Efron.Many thought that Zac Efron wasn't singing in The Greatest Showman, since the former Disney actor infamously didn't sing in the first musical in his career, High School Musical. Regardless, though, here's what we know regarding the actor and singer's involvement in the 2018 classic film.How much did Zac Efron actually sing in 'The Greatest Showman'? You'd be surprised.It's widely known that Zac was torn up over the fact that Drew Seeley sang for him in the first High School Musical movie, according to Life & Style Mag, but it seems as though that wasn't the case in The Greatest Showman. The Neighbors star was proud to say his singing voice was actually used in The Greatest Showman. He explained that he and his co-stars pre-recorded some of the songs as a "skeleton track," while other parts were sung live, in order to ensure the cadence and notes were on-point.He also explained they did it this way because sometimes they would find details that were missed in the initial recording. Occasionally, they would re-record tracks in the studio and add them in. Zac's co-star, Hugh Jackman, also noted that the beginnings of several songs are recorded live, because oftentimes, musicals mandate actors to transition from dialogue into singing pretty instantaneously. So bottom line: Zac sings in The Greatest Showman. We're all very proud.Zendaya presumably wasn't always singing during her epic trapeze scenes.During an appearance on The Tonight Show, Zendaya admitted that director Michael Gracey warned her ahead of rehearsals, saying that she should start working out ahead of time, in preparation for the rigorous trapeze rehearsals, because he wanted to use stunt doubles as little as possible. So according to Bustle, Zendaya started working out her upper body, and barely needed a stunt double for those wild trapeze scenes.That being said, singing and stunting on a trapeze certainly isn't conducive for top-notch singing, and therefore, it's assumed that some of her scenes used a vocal stand-in. However, there's also a chance Zendaya simply recorded all of her songs during trapeze scenes ahead of time. Either way, though, it's safe to say the Euphoria star worked incredibly hard to pull off her role in The Greatest Showman.We're thrilled that our beloved Zac finally got to jump back into musicals after his last singing role, which was as Troy Bolton in High School Musical 3. There's no denying that the former Disney star has some seriously solid pipes, after watching (and rewatching) The Greatest Showman a thousand times over, so we're definitely hoping he lands more singing roles in the future.