You can calculate principal and interest after each year. To start, what is the principal and interest at the end of the first year?

Alternatively, to find total interest, you need to calculate the total dollar times year amount and multiply it by 6.3%. For example, during the first two year the dollar times year amount is (2 years) * ($1000) + (1 year) * $1000 = 3000 buck-o-years. Therefore, the interest earned during the first two years is 3000 * 0.063 = $189.