A number problem for Kindergarten children to solve involving triangular numbers. We had been looking at different methods the children could use to solve number problems; e.g. drawing diagrams; using apparatus; making playdough models; etc.. They worked in pairs or small groups to encourage them to talk about their approach. The problem is easily differentiated by changing the final number. More able children and those in higher year groups could look at the pattern and think about rules for solving the problem regardless of the number given.