where m(t) is the mass of the material at a given time t, is the initial amount of mass m(0), is the half-life, and t is the time elapsed.

So we know that

We need to solve this for .

/day

So

We wish to find out when m(t) = 1 mg.

Solve this like the preceding problem. I get days.

So 76.4 days or so.

-Dan