Explain why mitosis is called equational and meiosis is called reductional division?

Mitosis is called equational division because number of chromosomes and amount of DNA in daughter cells remain equal to parent cells.

Example. If a parent cell has 18 chromosomes, then in daughter cells formed by mitosis have each 18 chromosomes.

Meiosis is called reductional division because number of chromosomes and amount of DNA in daughter cells is reduced to half than that of parent cell. In meiosis diploid number of chromosomes is reduced to haploid number.

Example. If a parent cell has 16 chromosomes then in daughter cells due to meiotic division number of chromosomes is reduced to eight.