please provide an explanation

XP 4-38 (similar to) Question Help You are saving for retirement. To live comfortably, you decide you will need to save $2 million by the time you are 66. Today is your 26th birthday, and you decide, starting today and continuing on every birthday up to and including your 65th birthday, that you will put the same amount into a savings account. If the interest rate is 4%, how much must you set aside each year to make sure that you will have $2 million in the account on your 65th birthday? The amount to deposit each year is $20237.48 (Round to the nearest dollar)