factorial
nounUK /fækˈtɔː.ri.əl/
US /fækˈtɔːr.i.əl/
The factorial of a number is that number multiplied by all the smaller whole numbers down to one.
The factorial of 4 is 24, because 4 × 3 × 2 × 1 equals 24.
OTHER MEANINGS
2. A mathematical function written with an exclamation mark, as in 5!, meaning the product of all positive integers up to that number.
She wrote 5! to mean 120.
3. Relating to a factor or factors.
The factorial design of the experiment tested several variables at once.
4. In statistics, a factorial experiment is one that studies the effects of multiple factors and their interactions.
They used a factorial design to compare the two treatments.