Definition
Inch
An inch is a customary unit of length equal to exactly 25.4 millimetres.
Continue from this idea into connected AXIO math.
What it means
Use inches for short lengths in customary measurement. Line up the object’s end with zero on the ruler, then read the mark at the other end.
Remember it
Twelve inch steps make one foot.
Example
Three strips are each 4 inches long. Together they measure 3 × 4 in = 12 in = 1 ft.
Watch for
The word 'in' is usually a preposition in sentences; it is a unit symbol only in clear measurement context.
Common mix-up
Do not start measuring from the ruler’s edge unless the zero mark is exactly there.
Exact meaning
The symbol in names the international inch. Its length is exactly 25.4 millimetres, and 12 inches make 1 foot.