Calculate the number 891
NUMBERMANIA: Calculate the number 891 using numbers [2, 4, 5, 4, 29, 130] and basic arithmetic operations (+, -, *, /). Each of the numbers can be used only once.Correct answers: 3
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Screw pointing and threading machine patentIn 1852, Cullen Whipple, of Providence, R.I., patented his "Mechanism for Pointing and Threading Screw-Blanks in the Same Machine" (U.S. No. 9477). His new design incorporated additional cutters in the same threading machine he had patented on 18 Aug 1842 (No. 2754, reissued 5 Mar 1850). Before machines provided a point on screws, they had blunt ends, and it was necessary to drill a starter hole. In Oct 1840, he was one of ten incorporators of The New England Screw Co. After his original thread-cutting machine, he invented another for shaving the heads of screws (patented 6 Apr 1843) and one for removing the burs left in cutting the slots in the heads (patented 19 Apr 1843). He patented seven other screw-manufacturing devices.« |