Each group of three <span>nucleobases</span>, when translated, will result in one amino acid. Considering that the coding region has 1800 base pairs, and only one side of the DNA strand is expressed, there will be only 1800 nucleobases that will take part on the gene expression and the protein translated will consist of 600 amino acids. It is only needed to divide 1800 by 3 (which is the number of nucleobases that will result in one amino acid). 
=600