Plus-Minus Sign
About Plus-Minus Sign
± is the plus minus symbol, a mathematical character indicating both positive and negative values of a number or quantity. The plus minus symbol ± is widely used across scientific and engineering disciplines to express measurement tolerances, statistical confidence intervals, and algebraic solutions. The plus minus symbol serves as an efficient shorthand for conveying range and uncertainty in a single compact notation.
The plus minus symbol ± consists of a plus sign above a minus sign, connected to form a single unified character. As a Unicode character, the plus minus symbol holds codepoint U+00B1 within the Latin-1 Supplement block, ensuring compatibility across most fonts and operating systems. The plus minus symbol can be typed quickly using keyboard shortcuts or character panels.
【Mathematical Applications】 The plus minus symbol was first systematically used by Albert Girard in 1626 to indicate the two possible roots of quadratic equations. Today, the plus minus symbol appears in algebra, calculus, and statistics. It frequently pairs with the sigma symbol σ in expressions like mean ± σ, using the plus minus symbol to denote one standard deviation from the average in normal distributions.
【Scientific and Engineering Uses】 Beyond pure mathematics, the plus minus symbol is essential in physics for expressing measurement uncertainty (e.g., 5.0 ± 0.1 meters), in engineering for specifying manufacturing tolerances (e.g., 10mm ± 0.5mm), and in data science for reporting confidence intervals. The plus minus symbol is also used in conjunction with the square root symbol √ when expressing both positive and negative square roots.
How to Type Plus-Minus Sign
Windows Input
Method 1: Hold Alt and type 0177 on the numeric keypad; Method 2: Type zhengfuhao in Chinese input method and select ± from candidates; Method 3: Use Character Map (charmap.exe) to find and copy the plus minus symbol.
Mac Input
Method 1: Press Option + Shift + = to directly type the plus minus symbol ±; Method 2: Press Control + Command + Space to open Character Viewer and search "plus minus"; Method 3: Use the keyboard viewer to locate the plus minus symbol.
HTML/CSS Input
HTML: ± or ± or ±; CSS: content: "\00B1";
LaTeX Input
Use \pm to type the plus minus symbol ± in LaTeX math mode. For text mode, use \textpm from the textcomp package or simply \text{\pm} for consistent rendering of the plus minus symbol.
Plus-Minus Sign FAQ
What does the plus minus symbol ± mean?
The plus minus symbol ± indicates that a value can be either added or subtracted, representing a range around a central value. For example, 100±5 means the value ranges from 95 to 105. The plus minus symbol is used to express both the positive and negative possibilities simultaneously.
How is the plus minus symbol used with the sigma symbol in statistics?
In statistics, the plus minus symbol is commonly paired with the lowercase sigma symbol σ to express standard deviation, such as mean ± σ. This usage of the plus minus symbol with sigma indicates data spread around the average within one standard deviation, covering approximately 68% of normally distributed data.
What is the difference between ± and ∓?
While the plus minus symbol ± means "plus or minus", the minus-plus symbol ∓ (U+2213) means "minus or plus". They are often used together in expressions like a ± b ∓ c to indicate that when the first operation uses plus, the second uses minus, and vice versa. The plus minus symbol is far more common in everyday mathematical notation.
How is the plus minus symbol used with the square root symbol?
When solving quadratic equations like x²=4, the solution is x=±√4, using the plus minus symbol alongside the square root symbol √ to indicate both the positive and negative roots. The plus minus symbol pairs naturally with the radical sign whenever a squared variable yields two possible solutions.