k1 subitizes (effortlessly/immediately/instantly counts the number in/recognizes the cardinality of) set k2 to be k3 [number/count], counted by/in terms of units k4
x1 (collection, body, set, mass, tuple, n-some, etc.) is x2 (li; default: 1) indivisible/atomic/elementary/basic discrete entities (or particles) of type x3 in composition/content, by standard x4; the count of instances of x3 in x1 is x2 by standard x4.