How many people are left-handed?
Studies vary slightly, but it is thought that about 10% of people are left-handed. The exact worldwide percentage is elusive both because the definition of left-handedness is flexible and because the rate of occurance may vary between cultures. Men are slightly more likely than women to be left-handed. There are also slightly positive correlations between left-handedness and some neurlogical disorders such as autism, dyslexia, and schizophrenia.1
Given a 10% occurance of left-handedness and that there are well over six billion people on Earth2, there are over six-hundred millon (600,000,000) lefties in the world!