Replace the question mark with a number
MATH PUZZLE: Can you replace the question mark with a number?Correct answers: 70
The first user who solved this task is Eugenio G. F. de Kereki.
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Frederick Gardner CottrellBorn 10 Jan 1877; died 16 Nov 1948 at age 71.American educator and scientist who invented the industrial electrostatic precipitator (1907), which eliminates suspended particles from streams of gases. He patented the “Art of Separating Suspended Particles from Gaseous Bodies” (No. 895,729). To electrochemists, he is best known for the Cottrell equation. Electrostatic precipitators are still widely used to reduce air pollution by smoke from power plants and dust from cement kilns and other industrial sources. Cottrell contributed to the development of a process for the separation of helium from natural gas, and also was instrumental in establishing the synthetic ammonia industry in the U.S. during attempts to perfect a high temperature process for formation of nitric oxide. |