How did we arrive at that? Recall all that you learnt about Interest.
For the first month, you would earn a 6% interest for a month on Rs. 1000, that would amount to Rs. 5 (Rs. 1000 x 6/100 x 1/12). Next month, you would put in another Rs. 1000, so your principal becomes Rs. 2005. So, you
would have earned Rs. 20.05 interest (Rs. 2005 x 6/100 x 2/12) in the second month. You would have Rs. 2020.05 at the end of two months and so it goes on for the next 10 months.
Had you put the money in a box at home, you would have lost out on the interest of Rs. 395. By investing your money rather than simply saving, you can have more money! How cool is that?