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Calculate the number 613

NUMBERMANIA: Calculate the number 613 using numbers [2, 8, 9, 4, 39, 538] and basic arithmetic operations (+, -, *, /). Each of the numbers can be used only once.

Correct answers: 17

The first user who solved this task is Nílton Corrêa de Sousa.

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First use of chemical symbols in British textbook.

In 1832, Edward Turner wrote a Preface to the 4th edition of his textbook, Elements of Chemistry (published 1833), in which he explained his use of symbols to represent reactants and products in a chemical reaction of Cyanogen, because he found they solved the difficulty of giving a “clear and concise description of. the phenomena in ordinary language.” His was the first use of chemical symbols in a British chemistry textbook. Turner used some algebra-type notation as suggested by William Whewell with parts of Jöns Jacob Berzelius's system, in which iron was represented by Fe (from Ferrum) and oxygen by O. Thus Fe + O represented one oxide of iron, and 2Fe + 3O represented another. Dots over the symbol indicated degree of oxidation, and an underline stood for two equivalents of a substance.«

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