350$ at 3% for 10 years. what is the interest earned?

If you are using continuous compound interest, the formula is A = Pe^RT where A= amount, P= principal value, R = the rate, and t = time. E is an actual number that is kinda hard to explain but it's just a button on the calculator. 

In this case the equation would be A = 350e^(0.03)(10). This gives you approximately 472.4506 or approximately $472.45 since it's money and you round to the nearest penny.