Basic grammar still has a place in our 160-character world.  "Buzzfeed" used the Online-Utility Readability Calculator to rank the literacy of the top ten most-followed people on Twitter.  The program, which calculates the average reading grade-level of text, said President Barack Obama's Twitter feed has the least amount of errors. 

Pop star Katy Perry was the runner-up, with her tweets ranked at the reading level of five-point-eight, followed by Lady Gaga, Ellen DeGeneres and Taylor Swift.  Justin Bieber was named the least literate, with his tweets coming in at a reading level below one.  Other top-followed stars who don't mind their grammar on Twitter are Rihanna and Justin Timberlake.  Shakira is also among the worst, but could be forgiven as English isn't her native language.