Abstract A positive integer n is called a Zumkeller number if the set of all the positive divisors of n can be partitioned into two disjoint subsets, each summing to σ(n)/2. In this paper, Generalizing further, near-Zumkeller numbers and k-near-Zumkeller numbers are defined and also some results concerning these numbers are established. Relations of these numbers with practical numbers are also studied in this paper.

Fermat's Last Theorem (FLT), (1637), states that if n is an integer greater than 2, then it is impossible to find three natural numbers x, y and z where such equality is met being (x,y)>0 in x n + y n = z n. This paper shows the methodology to prove Fermat's Last Theorem using Reduction ad absurdum, the Pythagorean Theorem and the property of similar triangles, known in the 17TH century, when Fermat enunciated the theorem.