You may change the single digit number midstream. This game can be played out loud, or pupils could write their answers on paper. Simply reverse the game to add a single digit number. Many Ways to Write a Number - Noggle. This is the numeric version of Boggle, the word game.
Third pupil gives the answer being the total of two numbers.
Then second pupil calls out a number, third pupil calls a number and fourth pupil gives answer. This continues until each pupil has had a chance to answer. Score 10 points for a correct answer. This could be modified for subtraction or multiplication.