(combinatorics) Any of the triangular array of natural numbers defined by N(n, k), n = 1, 2, 3 ..., 1 ≤ k ≤ n, occurring in various counting problems.

(mathematics) A natural number that cannot form a palindrome through the iterative process of repeatedly reversing its digits and adding the resulting numbers.

(number theory) A positive integer whose abundancy index is greater than that of any lesser positive integer. / Used other than figuratively or idiomatically: see superabundant, number.

A unique number which identifies a published book, for example, an ISBN.

(grammar) A numeral that expresses how many times some event happens.

plural of numbered list

A number assigned to each work composed by Wolfgang Amadeus Mozart.

(fluid mechanics) A dimensionless number (symbol We) that is useful in analysing fluid flows where there is an interface between two different fluids. It can be thought of as a measure of the relative importance of the fluid's inertia compared to its surface tension.

(genetics) The number of chromosomes in each cell of an organism

(mathematics) For some number n, the maximum number of regions into which a cube can be partitioned by exactly n planes.