From Cleave Books, we have TRoL (Teacher Resources on Line), known perhaps for its Calendar Models and also SCoL (Specialist Calculators on Line) covering topics such as: Mensuration of 2-D and 3-D shapes, percentages, growth and decay, and units; for example, under 2D shapes we have a right-angled Triangles and Sectors calculators.
These were created a considerable time ago; we could use WolframAlpha, for example, to check such calculations.
