Kindly Explain

I have Rs.100/- and I purchased rice of Rs.40/-, rest I've Rs.60/- then I purchased fruits of Rs. 30/-, rest I've Rs.30/, then I purchased cold drinks of Rs.18/, rest I've Rs.12/, Then I purchased some snakes of Rs.12/. Now just see, purchased :- 40+30+18+12=100, but at the same time if I calculate Rest :- 60+30+12+00=102, pl explain the difference of Rs.2/-.