half life means a substance gets reduced by 50 % of its value with in the half life period
Here suppose, a element of 100 g has half life of 300 years, so after 300 years, the weight of 100 gm element becomes 50 gm
Again after 600 years, the weight of element will be 50% of its current value thus, it would get reduced to 50/2 = 25 gm
as the weight of element becomes 1/4 of its actual value, the number of atoms also become 1/4th of its actual value.
