Kimberly borrows 1000 dollars from Lucy, who charged interest of 6% per month (which compounds monthly). What is the least integer number of months after which Kimberly will owe more than twice as much as she borrowed?
https://web2.0calc.com/questions/kimberly-borrows-dollars-from-lucy-who-charged-interest
Although this one is "..., who charged interest of 5% per month..." I know you can solve it with 6% per month!
