In the classroom, the teacher teaches mathematics. One of the students asked to teacher "When we add 2+7+9=? What is the sum of them? " The teacher answered him "The sum of 2+7+9 is 1" The student said how did you get madam. The madam proved to him "Look the spell of those numbers" And the teacher wrote the spelling of those numbers 2= Tw o 7= Seve n 9= Nin e The teacher "Now, the answers, you take all of the last words now the answer is one" Teacher proved.