What is the missing number?

A sixth grade class is doing some spelling drills. The teacher asks Tommy if he can spell 'before.' He stands up and says, "Before, B-E-P-H-O-R."

The teacher says, "No, that's wrong. Can anyone else spell before?"

Another little boy stands up and says, "Before, B-E-F-O-O-R."

Again the teacher says, "No, that's wrong." The teacher asks, "Little Johnny, can you spell 'before'?"

Little Johnny stands up and says, "Before, B-E-F-O-R-E."

"Excellent Johnny, now can you use it in a sentence?"

Little Johnny says, "That's easy. Two plus two be fore."