1. Compute the time it takes to save $10,000 if you know you can save $300 per month in a bank account paying 10 percent interest.

2. Compute the amount of money you need to invest today to have a balance of $10,000 10 years from now in a bank account expected to earn 10 percent interest.

3. You are saving $300 per month in a 5% account and want to know how much you will have for retirement.

4. You take out a mortgage of $200,000 for your house at 4% for 30 years. You want to compute your monthly P&I payment (principal and interest).