To calculate problems abound about compounding interest use the equation <span>A = P (1 + r/n)^<span>(nt), where A is the future price, P is the principal amount, r is the interest rate, n is the number of times the interest is compounded per year and t for the total years. To solve, A = 100 (1 + 0.08/1)^(1 x 15) = 317.22.</span></span>
2.43 + 1.62 + 124.77 = 178.82 Because all you have to do is add up all the numbers (Don't take the decimals out, leave them in) And then you get: 178.82.