What it means
The twenty-second Greek letter. Most readers meet it in the chi-squared test and distribution, χ². It is also magnetic or electric susceptibility and the Euler characteristic.
Read aloud in real formulas
χ² = ∑ (O − E)² / E
Aethel says
chi squared equals the sum of the quantity O minus E, squared over E
the chi-squared statistic, observed against expected counts
χ = V − E + F
Aethel says
chi equals V minus E plus F
the Euler characteristic of a polyhedron
Typing it
- LaTeX
- \chi (capital: X)
- Unicode
- U+03C7, U+03A7
Questions
How do you pronounce chi (χ)?
It is said “chi”, roughly KYE (rhymes with "sky").
What does χ mean in maths?
The twenty-second Greek letter. Most readers meet it in the chi-squared test and distribution, χ². It is also magnetic or electric susceptibility and the Euler characteristic.
How do you type χ?
In LaTeX, write \chi (capital: X). Its Unicode code point is U+03C7, U+03A7.
What is χ often confused with?
It is easy to mistake for the Latin x: χ has a curve, x does not.