What was the longest-running number one U.S. pop hit of the '80s?

Question: What was the longest-running number one U.S. pop hit of the '80s?
Many pop music milestones of the '80s belong to major artists like Madonna and Michael Jackson. However, it may surprise some to learn the artist responsible for the decade's longest-running number one American pop song.

Answer: Olivia Newton-John had made a name for herself during the '70s as an adult contemporary and country pop artist of some significance, but when she emerged in late 1981 with the unspoiled pop sound of "Physical," music fans embraced her more than ever before. For 10 weeks of the following winter, this playful, conceptual, slow-burning bit of ear candy ruled the charts, buoyed certainly by the sultry music video that established a newly sexy, provocative image for the Australian chanteuse. Though it still ranks as Newton-John's final No. 1 hit, "Physical" helped diversify the singer's appeal as more than a soft rock threat. Feel the burn.