A set of 25 staged assessments addressing every key learning target for basic arithmetic, from single figure additions to calculating cube roots. Online material to accompany these assessments can be accessed for free at www.mathsid.com, along with full instructions for use. Maths ID is a free to use website for numeracy teachers featuring interactive practice materials, printable assessment sheets, and progress tracking tools. Each of its three topics (Arithmetic, Money and Time) has 25 finely graded stages, which allow learners to build their knowledge incrementally and at their own pace. Maths ID allows for fully differentiated delivery even for the most diverse learner groups, automatically structures learning, and generates clear evidence of genuine progress. It will be especially useful for learners who require intensive work to develop the most essential numeracy skills, including learners with special educational needs.