Definition
A number system based on ten, in which each digit's value depends on its position relative to a decimal point. Whole numbers sit to the left of the point and fractional parts (tenths, hundredths, thousandths, etc.) sit to the right.
Plain English
The everyday counting system that uses the digits 0 through 9, with a dot to separate whole numbers from parts of a number — like 12.75.
Context Anchor
Seen in aviation maintenance math, measurement conversions, aircraft records, limits, and any written number that uses decimal places.
Derivation
From the Latin decimus, meaning 'tenth.' The system is called decimal because everything is grouped, divided, and counted by tens.
Why Pilots Care
Maintenance work constantly involves decimal measurements — torque settings, clearances, pressures, and tolerances. Misreading a decimal point can mean the difference between a correct setting and one that damages a component.
Intuition Check
Do not think of the decimal system as only “numbers with a dot.” The decimal point is part of it, but the decimal system is the whole base-10 way of writing numbers.
Example Sentence 1
The maintenance manual specifies the bolt torque as 27.5 foot-pounds, written in the decimal system.
Example Sentence 2
Technicians convert common fractions to the decimal system to set precise torque values on fasteners.