The genome of a person including the child is comprised of 23 pairs of the chromosome. Out of these 23 pairs, the child inherit one pair from his/her father and one pair from his/her mother. the 22 pairs of the chromosomes are autosomes, and one is allosome or the sex chromosome.
The mother always donates an X chromosome and autosomes and father donate either X or Y sex chromosome with 22 autosomes, which determines the sex of a child.
Hence, the child inherit 23 chromosomes from each parent, which makes 23 pairs or 46 chromosomes in the child.