What was Karen Carpenter's number 1 hit song?

Karen Carpenter often said, and there is written evidence to support this, that her favorite Carpenters' song was: "I Need To Be In Love". It was written and recorded in 1976, it was one of the songs on the "A Kind Of Hush" album, and there is a music video that uses it that shows Karen and Richard taking a plane and looking for love, but, not finding it.