2+2+2=7
Teacher: "If I gave you 2 cats and another 2 cats and another 2, how many will you have?"
Johnny: "Seven, Sir".
Teacher: "No, listen carefully. If I gave you 2 cats, and another 2 cats and another 2, how many will you have?"
Johnny: "Seven"
Teacher: "Let me put it to you differently. If I gave you 2 apples, and another 2 apples and another 2, how many will you have?"
Johnny: "Six".
Teacher: "Good. Now if I gave you 2 cats, and another 2 cats and another 2, how many will you have?"
Johnny: "Seven!!!"
A very angry Teacher: "Where the in hell do you get seven from"?!?!?
Very angry Johnny: "Because I've already got a friggin' cat at home"!!!