Calculate the number 759
NUMBERMANIA: Calculate the number 759 using numbers [9, 2, 3, 8, 88, 968] and basic arithmetic operations (+, -, *, /). Each of the numbers can be used only once.Correct answers: 1
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DuPreneIn 1931, The DuPont company, of Wilmington, Delaware, announced the first synthetic rubber. It was known as DuPrene, and from 1936 as Neoprene. Many scientists were trying to make natural rubber in the 1920s and 30s. One of the Wallace Carothers team, Gerard Berchet, had left a sample of monovinylacetylene in a jar with hydrochloric acid (HCl) for about five weeks. Then on 17 Apr 1930, coworker Arnold M. Collins happened to look in that jar and found a rubbery white material. The HCl had reacted with the vinylacetylene, making chloroprene, which then polymerized to become polychloroprene. The new rubber was expensive, but resisted oil and gasoline, which natural rubber didn't. It was the first good synthetic rubber.[Image: Wallace Carothers showing the new DuPrene product] |