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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Francis Edward ElmoreBorn 9 Nov 1864; died 26 Jul 1932 at age 67.British technologist who, with his brother Alexander Stanley El, jointly developed floatation processes to separate valuable ore, such as copper, from the gangue (worthless rock) with which it is associated when mined. In 1898, they obtained a patent for the first practical equipment (British patent No. 21,948). Pulverized ore is mixed with water and brought into contact with thick oil. The oil entraps the metallic constituents, which are afterwards separated, and gangue passed away with the water. They installed their equipment at mines in north Wales, northern England, and at the Broken Hill lead and zinc mines in Australia. Today, floatation methods remain vital in the mining industry, processing millions of tons of ores each year. |