You deposit $1000 in an account that pays 3.5% annual interest compounded monthly. When is your balance at least $3500

FV = PV x [1 + R]^N

3,500 = 1,000 x [1 + 0.035/12]^N       divide both sides by 1,000

3.5 = [1 + 0.00291666667]^N

3.5 = 1.00291666667^N                      tale the log of both sides

N =log(3.5) / log(1.00291666667)

N =430.14 months =~35 years and 10 months for $1000 to grow to $3,500 @3.5% comp. monthly.