These are KS2/3 questions in calculations involving negative numbers. The two spreadsheets present the class with a single question at a time on the screen. They also select a student at random to answer them. I use them to play games such as last (wo)man standing. They work well with whiteboards where the students write their answers and reveal them if their number comes up. It's an excellent way of ensuring everyone is answering the questions and a good way to find out who does not understand. One spreadsheet deals with adding and subtracting whilst the other generates random questions in all four operations. Invent your own games to go with them!