kiwiland, it doesnt matter on what four pieces the stone broke into. but for ur sake lets assume it broke into 35+2+2+1 now, to get the weight of the Rice, just place the rice in one side of the balance and the wieght in other side of the balance, you know the weight of the balance so, the only thing is whatever the balance shows you, just subtract it from the weight.. for example, if it shows 13 on the balance with the rice on it, then the wieght wud be.. 35-13= 22 did i get it right :p