Cash for questions activity

There are 4 sets of questions (Number; Algebra; Shape; Data) (with some lower grade questions from topics which students struggle with; e.g. percentages; constructions). Students work in pairs or small groups to answer the questions. When they finish a question they get it marked and if it is correct they are given cash to the value of the question. There are bank notes which you can put your school name and pictures of your teachers on. The team with the most money at the end could be given a prize.