How long will it take your money to grow from $9,000 to $50,000 if the interest is compounded monthly at 10% APR?

FV = PV [1 + R]^N

50,000 = 9,000[1 + 10/1200]^N    divide both sides by 9,000

5.5556 = [1 + 0.0083333]^N

5.5556 = [1.0083333]^N                take the log of both sides

N = Log(5.5556) / Log(1.0083333]

N = 206.63 months, or about 17 years and 3 months.