Factor Stencils by Derrick N. Lehmer
date: label: date made
content: ca 1929
name: label: maker
content: Lehmer, Derrick Norman
notes: label: Description
content: Derrick Norman Lehmer (1867–1938) was a distinguished American number theorist. Born in Somerset, Indiana, he obtained his BS from the University of Nebraska in 1893, taught there and at a Nebraska academy for a time, and then moved on to the University of Chicago where he studied with E. H. Moore. After obtaining his PhD in 1900, he was hired by the University of California at Berkeley, rising through the ranks until his retirement in 1937. Assisted by the Carnegie Institution of Washington, Lehmer developed this set of factor stencils to aid in factoring large numbers.
label: Description
content: Each sheet is for a different quadratic residue, R. At the very top of each sheet is printed: R=. Different values of the quadratic residue R have been typed in next to the equals sign. Values range from R= -238 to R= -1 and from R= +3 to R= +238, with one stencil for each value of R. Values of R for which there are stencils correspond to those for which there are sets of punched cards in object 1988.0316.02. (The set of cards includes some higher values of R.) There are a total of 295 sheets. The sheets have fifty columns and 100 rows, allowing a position for each of the first 5000 prime numbers. If a prime number had a given quadratic residue, a hole is punched in the corresponding position on the sheet. Superimposing the sheets assisted in finding numbers with a group of quadratic residues, and greatly reduced the time required for factoring.
label: Description
content: Working with his son, number theorist D. H. Lehmer, D. N. Lehmer went on to develop an electric version of the factor stencils, which was exhibited at the Chicago World’s Fair in in the 1930s.
label: Description
content: Reference:
label: Description
content: Derrick N. Lehmer, <I>Factor Stencils</I>, Washington, DC: Carnegie Institution of Washington, 1929.
label: Location
content: Currently not on view
place: label: place made
content: United States: District of Columbia, Washington
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
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content: Science & Mathematics
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content: Mathematical Association of America Objects
creditLine: label: Credit Line
content: Gift of Columbia University Libraries
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1988.0316.01
label: accession number
content: 1988.0316
label: catalog number
content: 1988.0316.01
objectType: label: Object Name
content: sheets, set of
physicalDescription: label: Physical Description
content: paper (overall material)
label: Measurements
content: overall: 6 cm x 22.8 cm x 45.5 cm; 2 3/8 in x 8 31/32 in x 17 29/32 in