Our familiar + and - signs were not used until only four to five hundred years ago. Diophantus of Alexandria and the Hindus (seventh century A.D.) indicated addition by simply placing all the quantities to be added side by side. Subtraction was similar.
Diophantus used the symbol, , followed by all the negative terms, side by side, to indicate subtraction. The Hindus indicated subtraction by placing a dot over the quantity to be subtracted (the subtrahend).
In the late fifteenth and early sixteenth centuries, some of the Italian mathematicians introduced symbols into their algebra. Luca Pacioli used a p (from piu, "more") for plus, and m (from meno, "less") for minus in his Summa de arithmetica of 1494.
The + and - symbols first appeared in print in Leipzig in 1489 in an arithmetic by Johann Widman. Here the symbols were used to indicate excess and deficiency, not the addition and subtraction operations of today. In 1514 the Dutch mathematician Vander Hoecke used the + and - symbols for algebraic operation, but it is believed they were used this way even earlier.
It is thought that the plus sign is a contraction of the Latin word et, which was often used to indicate addition. The minus sign is believed to be from the abbreviation of for minus.