Definition
The number written above the line in a common fraction, indicating how many parts of the whole are being considered.
Plain English
In a fraction, it's the top number. It tells you how many pieces you have out of the total.
Context Anchor
Seen in maintenance math, measurements, ratios, and formulas that use fractions.
Derivation
From the Latin numerare, meaning 'to count.' The numerator is literally the 'counter' — it counts how many parts of the whole you are dealing with.
Why Pilots Care
Maintenance technicians and pilots work with fractions constantly — torque values, measurements, mixture ratios, fuel calculations. Mixing up the numerator and denominator changes the answer entirely and can lead to incorrect torque, wrong measurements, or miscalculated loads.
Analogy
In the fraction 3/4, think of four equal pieces with three of them selected. The 3 is the numerator because it counts the selected pieces.
Intuition Check
If you see 3/4, the numerator is the 3 (top). The denominator is the 4 (bottom). Top counts the parts you have; bottom names the size of the parts.
Example Sentence 1
In the fraction 5/8 inch, the numerator is 5, indicating five eighth-inch units.
Example Sentence 2
In a weight-and-balance moment, the numerator of the arm fraction is multiplied by the item weight.