Definition
Numbers that carry a positive (+) or negative (−) value, indicating direction or sense relative to zero. Positive numbers are greater than zero; negative numbers are less than zero. In aviation maintenance mathematics, signed numbers are used to represent quantities that can move either way from a reference point, such as temperatures above or below freezing, voltages above or below ground, or measurements above or below a datum.
Plain English
Numbers with a plus or minus in front of them. The plus or minus tells you which side of zero the number is on, and which direction it goes.
Context Anchor
Seen in aviation maintenance math, electrical measurements, and digital system discussions where a value may be above or below zero.
Derivation
From the word 'sign,' meaning a mark that gives information. The 'sign' of a number is the small mark (+ or −) that tells you whether it is above or below zero.
Why Pilots Care
Getting the sign wrong flips the answer. A miscalculation with negative numbers can lead to a wrong torque value, wrong voltage reading, or a weight and balance result that points the wrong way.
Analogy
Think of a thermometer. Numbers above zero are positive; numbers below zero are negative. The sign tells you which side of the freezing line you're on.
Intuition Check
“Signed” does not mean approved or handwritten here. It means the number carries a plus or minus direction from zero.
Example Sentence 1
When adding signed numbers, the technician noted that −5 plus +8 equals +3.
Example Sentence 2
When calculating battery voltage changes, the mechanic recorded both positive and negative values as signed numbers.