Amazing tool to compute formulas & build graphs. Allows to input expressions in LaTeX-like format, has built-in statistic functions. Drag the points on a plot:
Has a lot of functionality. Irreplaceable for matrices operation in algebraic not numerical form. Input is a bit less convenient than Desmos, but matrices are only Desmos serious flaw.
Tools below are best for happy owners of iPads or Samsung Notes supporting pen.
You can add multiuser handwritten updates to the same note in realtime. Drag&drop vector graphics, images and icons.
Keep an active part of a note opened on a table while whole the rest of it on a huge screen in front of you.
Cost $10 / month. Shows changes you make, like added images or hand-written formulas in real-time. Allows easily add cool icons / vector arrows and many other things. Not always perfectly works with pen input:
Free. Best for daily notes. Notes undistinguishable from the real paper. Nice organizing. Few times a day has cross-devices sync delays up to 5-10 minutes. So not perfect for a realtime collaboration.