  ## Math SymbolsThe Most Valuable and ImportantMiscellaneous Symbols. . .Shown and Explained"Plus-Minus Sign" Plus-Minus Sign . . .

Background - why symbols are used . . .

Symbols are used as a concise way of giving lengthy instructions

related to numbers and logic.

Math Symbols are a communication tool. Symbols are an invention which is used to eliminate the need to write long, plain language instructions to describe calculations and other processes.

The most valuable, most frequently used Symbols in
mathematics . . .
:

The most important, most frequently used Miscellaneous symbols are listed below.

Miscellaneous Symbols - click description Go To
"All Math Symbols"  The symbol means that the number (to the right of the symbol) is really two numbers: a positive number AND a negative number.

For Example, 8 stands for two numbers:

+8 and -8

The symbol is commonly used:

(1) In mathematical expressions and equations.

(2) To quantify the margin or error (precision) of a computation or measurement.

Example 1: , use in Mathematical Expressions and Equations

Square Root: The use of the plus-minus symbol is a short hand way of showing that the square root of 256 has two answers: Absolute Value: This absolute value equation can be rewritten using the plus-minus symbol: The use of the plus-minus symbol clearly shows that two equations must be solved to determine the values of x which satisfy the original equation. These equations are:  The use of the plus-minus symbol shows that two equations must be solved to determine which values of x satisfy the quadratic equation. These equations are:

(1) Using the "plus" sign: (2) Using the "minus" sign: Example 2: , use in "Precision" or "Margin or Error"

Margin of Error:

A local poll taken May 1-4 of 1200 registered voters showed Candidate A would beat Candidate B if the election were held now, 60 to 30 percent, with seven percent undecided. This poll has a margin of error of plus or minus four percentage points.

Candidate A should receive between 56% and 64% of the vote if the election were held today.

This could be written:

Candidate A
Likely Vote Engineering Tolerance:

A round pin is being manufactured to fit into a round hole, which is 20 mm in diameter. The round pin might have a manufacturing specification of 19.95 mm to 19.99 mm in diameter.

Using the plus-minus sign, this could be written:

Diameter of
Round Pin  