Definition
The mathematical symbol √ used to indicate that the root of a number is to be extracted. By default it indicates a square root; a small number written above and to the left of the symbol (the index) indicates a different root, such as cube root or fourth root. The number under the symbol is called the radicand.
Plain English
The √ symbol that tells you to find the root of a number — most commonly the square root, meaning the number that, when multiplied by itself, gives the value shown.
Context Anchor
Seen in basic math used for aviation maintenance calculations, especially when working through formulas in a handbook or manual.
Derivation
From the Latin radix, meaning 'root.' The symbol √ is thought to be a stylized form of the letter r (for radix). Knowing this helps explain why the operation is called 'taking a root' — you are finding the number at the base of a squared or cubed value.
Why Pilots Care
Maintenance technicians and pilots routinely use formulas containing roots — for example, calculating the side of a square area, working out cable tension, or applying physics formulas. Misreading the radical sign produces large numerical errors.
Intuition Check
Radical does not mean extreme here. It means root, as in finding the square root of a number.
Example Sentence 1
The technician applied the radical sign in the formula to find the square root of the area and determine the length of one side.
Example Sentence 2
Several formulas in the manual require the radical sign when solving for roots.