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Raphael M. Robinson
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African Americans demonstrating for voting rights in front of the White House as police and others watch, March 12, 1965. One sign reads, "We demand the right to vote everywhere." Voting Rights Act, civil rights.
Timeline of the American Civil Rights Movement
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Estimated Battle Casualties During the Normandy Invasion and Campaign to Liberate Paris (June–August 1944)
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Artist interpretation of space asteroids impacting earth and moon. Meteoroids, meteor impact, end of the world, danger, destruction, dinosaur extinct, Judgement Day, Doomsday Predictions, comet
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Normandy Invasion: Omaha Beach. World War II. D-Day. Infographic. SPOTLIGHT VERSION
Facts and Figures About the Landings on Omaha Beach During the Normandy Invasion on June 6, 1944
Salem Witch Trials. Photogravure after the painting by Walter McEwen titled - The Witches - circa 1890s.
How Rye Bread May Have Caused the Salem Witch Trials
Lake Mead (the impounded Colorado River) at the Hoover Dam. The light-coloured band of rock above the shoreline shows the decrease in water level in the first few years of the 21st century.
6 Lakes That Are Drying Up

Raphael M. Robinson

American mathematician

Learn about this topic in these articles:

research on perfect numbers

  • See an explanation on Zeno's Achilles paradox, an infinite series concept used in finance to pay off mortgages
    In number game: Perfect numbers and Mersenne numbers

    mathematician Raphael M. Robinson had applied Lucas’ test and, by means of electronic digital computers, had found the Mersenne primes for n = 521; 607; 1,279; 2,203; and 2,281, thus adding five more perfect numbers to the list. By the 21st century, more than 40 Mersenne…

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