8.630 x 10^14
U can hav an infinite amount of zeros if they are trailing zeros. We all call them ambiguous.
Answer:
2 half lives.
Explanation:
Suppose there are 100g of parent isotope at the start.
After 1 half-life there will be 50g of parent and 50g of daughter isotope.
After another half life there is 25 g of parent and 75g of daughter isotope.