I now have $$18,000$ in the bank earning interest of $0\mathrm{.}50\%$ per month. I need $$28,000$ to make a down payment on a house. I can save

an additional $$100$ per month. How long will it take me to accumulate the $$28,000?$

Note: Do not round intermediate calculations. Round your answer to $2$ decimal places. Use a financial calculator or Excel.