I read this article.

Casio Japan: In 1985, Casio Japan invented the graphing calculator, called the Casio FX-7000.   Because of his invention, he has given students the ability to develop the connection between graphs and their formulas.  Also, by using all the different tools on Japan’s machine, the process of solving many mathematical problems has become simlipified.

Chester Carlson: In [...]

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