(mathematics, chiefly historical) Synonym of pi, particularly the 35-decimal approximation discovered by Ludolph van Ceulen

(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.

Synonym of split-complex number

(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.

plural of numbered list

(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.

(number theory) An algebraic integer that represents an ideal in the ring of integers of a number field.

(mathematics) The number of possible lattice paths from the southwest corner (0, 0) of an n × n grid to the northeast corner (n, n), using only single steps north, northeast or east, and not rising above the southwest–northeast diagonal.

(mathematics) For a given number n, the number of different ways of drawing non-intersecting chords between n points on a circle (not necessarily touching every point by a chord). They have diverse applications in geometry, combinatorics, and number theory.