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Boosted by cstanhope@social.coop ("Your friendly 'net denizen"):
guyjantic@infosec.exchange ("Still Mad About CD Prices") wrote:

Random thing I found at a #ThriftStore: Self-Adding E-Z Average finder.

This is my most adorable non-human #computer.

#RetroComputing #OldSchool #Statistics #Rstats #teaching #grading

Attachments:

• video: Video of use of the "Self-adding E-Z Average Finder", which is a piece of thin cardboard about the size of a large paperback novel, with a transparent plastic ruler-type thing anchored at the lower left so it pivots up and down. In concentric arcs outward from that pivot there are curved sections numbered 3 through 12 (indicating the number of items to be averaged) and a sliding plastic window on transparent ruler "arm" that pivots. The transparent window is placed so that, when the arm pivots, it does so along the numbers written on one of the arcs (e.g., if you want to average 7 numbers you place the window so it cruises along the "7" arc). There is a separate piece of circular cardboard bonded to the pivot, about two inches in diameter, labeled "Answer Wheel" and "Average Grade." The video shows usage of this cute device: the arm is placed at the lowest point (pivoted all the way "down" toward the user) with the Answer Wheel aligned at "100" with the center line of the arm/ruler thing. The video shows seven numbers (hypothetical test grades) on a post-it note. The user holds the answer wheel in place while rotating the arm so that, on the "7" arc, the first grade (in this case 67) is directly under the line along the transparent answer wheel, on the "7" arc. The user repeats the process with the rest of the numbers. After doing this, the video zooms in on a terminal running R on a computer screen. The answer on the E-Z average finder is close to what R calculated.