A twitching eye can be one sign of stress, especially when it is related to vision problems such as eye strain (see below). Reducing the cause of the stress can help make the twitching stop. Tiredness: A lack of sleep, whether because of stress or some other reason, can trigger a twitching eyelid.
C(n,k) is the number of combinations you can make of k objects out of a given set of n objects. We see that C(n,0) and C(n,n) should be equal to 1, but they require that 0! be used. So 0! = 1 neatly fits what we expect C(n,0) and C(n,n) to be.(n,k) is the number of combinations you can make of k objects out of a given set of n objects. We see that C(n,0) and C(n,n) should be equal to 1, but they require that 0! be used. So 0! = 1 neatly fits what we expect C(n,0) and C(n,n) to be.
The number Ï is a mathematical constant, the ratio of a circle 's circumference to its diameter, commonly approximated as 3.14159. It has been represented by the Greek letter  Ï  since the mid-18th century, though it is also sometimes spelled out as  pi  (/paÉª/).ome people use a different value, Ï = 6.283185... = 2 Ï, arguing that Ï, as the number of radians in one turn or as the ratio of a circle's circumference to its radius rather than its diameter, is more natural than Ï and simplifies many formulas.