Interesting fact:

What's your favorite number? Chances are it's 7. In a recent online poll of 3,000 people, nearly 10% chose 7 as their favorite number, with the number 3 coming in at second. Seven might be so popular because it's connected to many favorable things. It's also arithmetically unique in that it is the only single number you can't multiply or divide without keeping the answer between 1-10.