mysterey number

Every day the class does mysterey number for maths. So what you do is your teacher picks three students to pick a number.
Then you count in any number(the teacher pick a number to start and end)Then when you get to the number that the teacher picked for the ending you would say BLASTOFF!!!!!!!!!. Then the student with the coset number get a sticker. After that some of the class students same a sum to get to the mysterey number.