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Abhay Ambale

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last 3 solved tasks
What will be the missing number? (9, 19, 40, ?, 170)
MATH PUZZLE: Can you replace the question mark with a number?

Vacuum tube

In 1906, Dr. Lee DeForest (26 Aug 1873 - 30 Jun 1961), one of the “fathers of radio,'' announced his three-element electrical vacuum tube (now known as a triode) to a meeting of the American Institute of Electrical Engineers He had discovered that when a mesh, or grid, of wire was placed between the filament and collector “plate” in a diode tube (first made by J. Ambrose Fleming, 1904), a large voltage-amplifying effect could be produced. DeForest patented this vacuum tube on 15 Jan 1907. The ability of this tube to amplifiy weak signals was an invention as great as radio itself, because it made long-distance communication possible.[Image: early DeForest Audion]

Invisible man

Nurse: "The invisible man is here for his appointment."
Doctor: "Tell him I'm sorry I can't see him right now."
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