9,100 is the answer if you do the work so i failed for yall you welcome
I'm not sure what your question is. But, the half life is the amount of time required for half the material to decay. For U238 this is 4.5 billion years, whilst for Fr-223 (Francium) its about 22 minutes. To calculate the time for something to decay you need to use the equation:
Mass (after time t) = Mass (initial) * (0.5)^(time/half life)
Hope this helps
If we keep cutting down tree's and if there are enough forest fires then it will turn into a desert....Hope it helps!