Definition
The result obtained by adding two or more numbers or quantities together; the total.
Plain English
What you get when you add numbers together. The total.
Context Anchor
Seen in maintenance math, weight-and-balance calculations, electrical load calculations, and measurement work.
Derivation
From the Latin summa, meaning 'highest' or 'total amount.' Romans wrote columns of numbers from bottom to top, so the total appeared at the top — the 'highest' figure on the page. That sense of 'the total of added amounts' is exactly how it's used today.
Why Pilots Care
A wrong sum can lead to a wrong maintenance result, such as an incorrect total weight, incorrect load, or incorrect measurement.
Intuition Check
Do not treat a sum as an estimate or an average. A sum is the exact total found by addition.
Example Sentence 1
The technician calculated the sum of the individual component weights to verify the total assembly weight.
Example Sentence 2
The technician calculated the sum of the current readings on each phase of the alternator output.