I’m not quite sure where the non-integer values are showing up on slide 3. Are you seeing it happen if the students were to type in the complete expression like this?
If this is what you mean, then I don’t think you can avoid this happening. I would suggest using cellDisableEvaluation for each cell and then adding a third column that gives the numericValue of the expression in column 2. For example, you can use this for the last row to get the value of the expression in column 2:
cellContent(5,3): when isDefined(this.cellNumericValue(5,2)) "${this.cellNumericValue(5,2)}" otherwise ""