Click Reset.
Click Play/Run and let the simulation run until it stops.
Select the TABLE tab and record the number of radioactive atoms at each given time below.
Time | Number of Radioactive Atoms
-----|----------------------------
0 | 100
1 | 80
2 | 64
3 | 51
4 | 40
5 | 32
6 | 25
7 | 20
8 | 16
9 | 12
10 | 10