**Deficient number** — In number theory, a deficient number or defective number is a number n for which the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n)<n. The value 2n − σ(n) (or n − s(n)) is… … Wikipedia

**deficient number** — noun : an imperfect number (as 8) that is greater than the sum of its divisors * * * Math. a positive number that is greater than the sum of all positive integers that are submultiples of it, as 10, which is greater than the sum of 1, 2, and 5.… … Useful english dictionary

**deficient number** — noun A number that greater than the sum of all of its divisors except itself. The factors of 22 are 1, 2 and 11 and 22, and 1 + 2 + 11 = 14, which is less than 22, so 22 is a deficient number. Syn: defective number … Wiktionary

**deficient number** — Math. a positive number that is greater than the sum of all positive integers that are submultiples of it, as 10, which is greater than the sum of 1, 2, and 5. Also called defective number. Cf. abundant number, perfect number. [1720 30] * * * … Universalium

**Deficient** — De*fi cient, a. [L. deficiens, entis, p. pr. of deficere to be wanting. See {Defect}.] Wanting, to make up completeness; wanting, as regards a requirement; not sufficient; inadequate; defective; imperfect; incomplete; lacking; as, deficient… … The Collaborative International Dictionary of English

**Deficient-ly** — Deficient De*fi cient, a. [L. deficiens, entis, p. pr. of deficere to be wanting. See {Defect}.] Wanting, to make up completeness; wanting, as regards a requirement; not sufficient; inadequate; defective; imperfect; incomplete; lacking; as,… … The Collaborative International Dictionary of English

**number game** — Introduction any of various puzzles and games that involve aspects of mathematics. Mathematical recreations comprise puzzles and games that vary from naive amusements to sophisticated problems, some of which have never been solved.… … Universalium

**Perfect number** — In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect… … Wikipedia

**Abundant number** — In mathematics, an abundant number or excessive number is a number n for which σ ( n ) > 2 n . Here σ ( n ) is the sum of divisors function: the sum of all positive divisors of n , including n itself. The value σ ( n ) − 2 n is called the… … Wikipedia

**perfect number** — Math. a positive number that is equal to the sum of all positive integers that are submultiples of it, as 6, which is equal to the sum of 1, 2, and 3. Cf. abundant number, deficient number. [1350 1400; ME] * * * ▪ mathematics a positive… … Universalium