Haploid numbers refer to the number of chromosomes in an egg or sperm cell, and it has the abbreviation "n." Diploid numbers refer to the number of chromosomes in other types of cells, such as the zygote that appears when the sperm cell fertilizes an egg, abbreviated "2n."
For any organism, the diploid number is twice the haploid number because it is the sum of the haploid sets coming from the chromosomes of each parent. In the human species, the diploid number is 46, which means that 2n = 46. The haploid number, or n, is 23. In other species, the haploid and diploid numbers vary.
Rhesus monkeys and other members of the genus Macaca have a haploid number of 21 and a diploid number of 42. Some spider monkeys also have the same chromosomal numbers, as hooded spider monkeys, black-face spider monkeys and golden spider monkeys all have a haploid number of 17 and a diploid number of 34. Red titis, red uakaris, red-tailed tamarins, silky marmosets and saki monkeys all have haploid numbers of 23 and diploid numbers of 46, just like their human counterparts. Other species have even more chromosomes at work than humans, as green monkeys feature haploid numbers of 30 and diploid numbers of 60.