Free! When CALKOO first dropped on the radar, we thought Desmos might have a little competition. As it turns out, Calkoo is something completely different. It offers a collection of online calculators that forgo fanciful graphics and scaffolded computations in a favor of plain, fast results. Need to find a 10-year bond yield? Perform a cash flow analysis? Check and check. Don’t worry, it still has more traditional calculators for performing trigonometry or calculating quadratic equations, but we’re enchanted with the idea of starting with the results first, and working through concepts as students deal with real (though mostly first world) problems.