This widespread harebrained idiom has been traced back to a high school football coach of the 1950s. It certainly wasn't coined by a math teacher. The coach used it to exhort his players to do more than they thought they were capable of. To succeed, giving "just" one hundred percent would not suffice.
Inflation was bound to set in. Sure enough, today even a "hundred and ten percent" effort does not always get the job done. Now you must give "one hundred and twenty percent," "one hundred and fifty percent," "two hundred percent," and even "one thousand percent." Can "one thousand and ten percent" be far behind?