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aysan saidie

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last 3 solved tasks
If 8638+7542=664 and 5589+2468=872 then 1357+1919=?
If 5+7+2=68, 8+6+1=48 and 3+4+5=58 then 7+3+4=?
MATH PUZZLE: Can you replace the question mark with a number?

Friedrich Ernst Dorn

Born 27 Jul 1848; died 13 Jun 1916 at age 67.German physicist who was prompted by Madame Curie's discoveries to make his own study of radioactivity. In 1900, he observed that radium emitted both radiation and a colourless radioactive gas. The gas was accumulating inside ampules of radium. He called itradium emanation. (William Ramsay named it niton when he investigated it in 1908. This element was named radon, in 1923, the heaviest in the noble gas group.) Dorn had demonstrated one element transmuting to another, while releasing radiation. This work was continued by Boltwood and Soddy. Radon is not totally inert, as since 1962, chemists have been able to make radon compounds. In 1899, the release of a radioactive gas was detected by Ernest Rutherford and R.B. Owens from thorium (now known to be radon-220), and by the Curies from radium (radon-222).«Radon was first detected in 1899 as a radioactive gas released from samples of thorium by Ernest Rutherford and R.B. Owens. In the same year, the Curies detected a radioactive gas coming from the radium in their experiments.

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