Learn & Understand

Where the Plus and Minus Signs Came From

The basic calculator performs the four operations of arithmetic through symbols so familiar, plus, minus, times, divide, that they feel eternal. They are not. For most of history, calculations were written out in words, and the compact signs we now take for granted were invented, one by one, over centuries, by mathematicians seeking a faster way to write. Understanding where these symbols came from reveals that even the most basic arithmetic notation is a human invention, refined over time into the shorthand the calculator relies on.

Arithmetic Written in Words

Long before symbols, sums were described in prose. A calculation that we would now write in a few characters was once a sentence: this many added to that many, and so on. This made mathematics slow to write and hard to scan, and it tied arithmetic to particular languages. The invention of compact symbols was a quiet revolution, because it let a calculation be written and understood at a glance, independent of any spoken tongue. The signs on the calculator's keypad are the fruit of that long move from words to notation.

Plus and Minus

The signs for addition and subtraction emerged in the late medieval and early modern period, gradually replacing written words and older abbreviations. Once adopted, they spread because they were so obviously convenient, a single mark standing in for "add" or "subtract." Their simplicity is part of why they endured: easy to write, hard to confuse, and instantly recognizable. That a plus and a minus can now be read the world over, in any language, is a testament to how completely these once-novel symbols won out over the wordy alternatives they replaced.

Times and Divide

The signs for multiplication and division came along their own paths. Multiplication acquired more than one symbol over time, which is why a cross, a dot, and other marks have all served the same purpose, a reminder that notation is a matter of convention rather than necessity. The division sign, with its bar and two dots, is itself a small picture of a fraction. These symbols too competed with rivals before settling into common use, and their adoption was never quite as universal as plus and minus, which is why several notations for multiplication persist today.

The Power of Good Notation

The story of these four signs illustrates a deep truth: good notation is not mere decoration but a tool that makes thinking easier. By compressing operations into single marks, the symbols let the mind grasp a calculation whole, freeing attention for the reasoning rather than the writing. The calculator carries this inheritance in its simplest form, applying the four operations that everything else in mathematics is built upon, expressed through symbols that were themselves once new. Every sum it computes rests on centuries of gradual refinement in how humans chose to write down the act of counting and combining.

For roots, powers, and trigonometry in one place, see the Scientific Calculator; to work directly with parts of a whole, the Fraction Calculator.