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+

Nicole d' Oresme (1323-1382) may have used a figure which looks like a plus symbol ( + ) as an abbreviation for the Latin et (meaning "and") in Algorismus proportionum, believed to have been written between 1356 and 1361. The symbol appears in a manuscript of this work believed to have been written in the fourteenth century, but perhaps by a copyist and not Oresme himself.

The + and - symbols first appeared in print in Mercantile Arithmetic or Behende und hüpsche Rechenung auff allen Kauffmanschafft, by Johannes Widmann (born c. 1460), published in Leipzig in 1489. However, they referred not to addition or subtraction or to positive or negative numbers, but to surpluses and deficits in business problems (Cajori vol. 1, page 128).

The plus and minus symbols were in use before they appeared in print. For example, they were painted on barrels to indicate whether or not the barrels were full.