(genetics) The number of copies of a gene or plasmid within a cell's genome. / (library science) The identification number assigned to a specific copy of a work.

plural of number line

(mathematics) A line that graphically represents the real numbers as a series of points whose distance from an origin is proportional to their value

(topology, algebraic topology) Any of a sequence of numbers, denoted bₙ, which characterise a given topological space K by giving, for each dimension, the number of holes in K of said dimension; (formally) the rank of the nth homology group, Hₙ, of K.

(mathematics) By means of, or in terms of, number theory.

(graph theory) the number of edges in a maximum matching, often denoted 𝜈=𝜈(G)

(graph theory) the number of vertices in a maximum independent set of a given graph, often denoted as 𝛼=𝛼(G)

(graph theory) the number of vertices in a minimum dominating set of a given graph, often denoted as 𝛾=𝛾(G)

(graph theory) The number of vertices in a minimum vertex cover of a graph, often denoted as 𝜏=𝜏(G).

(Britain) Either of a pair of rectangular metal plates bearing an alphanumeric code, fixed to the front and rear of a motor car to show its identity as registered with the DVLA.