“＋”，加号是１５世纪德国数字家魏德美创造的。在横线上加一竖，表示增加。“－”，减号也是魏德美创造的。从“＋”号上减去一竖，表示减少。“×”，乘号是１８世纪美国数学家欧德莱最先使用的。它的意思是表示增加的另一种方法，因而把“＋”号斜过来写。“÷”，除号是 “+”, Plus was created by Wei Demei, a German digitalist in the 15th century. Add a vertical line, said the increase. “-”, minus is created by Wei Germany and the United States. Subtract erect from the “+” sign to indicate a decrease. “×”, the multiplication sign was first used by the American mathematician Attlee in the 18th century. It means another way of saying an increase, so write the “+” sign. “÷”, except the sign is