Ok I've tried to google this but no luck their. I'm writing a program that calculates someones consumer loan. If we use $1000 as principle, and 15%(.15) as the rate and the duration of the loan is 18 months, you would in the end only get $775 because the the interest is deducted from the principle leaving you with 775$ from $1000. The user enters their own principle, rate, and time, and the program is suppose to calculate how much to request by adding an extra to the principle. For example: If I want a $1000 loan(15%int. 18 months duration) and the interest is taken out at the time of the loan I would only get $775. I need to come up with a number for them to request to get the $1000 loan they need. So does anyone know of an equation that I could use to calculate any principle, rate, time to come up with the requested loan amount they need to ask for. Thank You!