We can start with the $100.
100 × 1/2 = 50
(You can also just divide the number by 2)
50 ÷ 2 = 25
25 ÷ 2 = 12.5
12.50 ÷ 2 = 6.25
6.25 ÷ 2 = 3.13 (it was 3.125 but we can round up to the nearest cent)
3.13 ÷ 2 = 1.56
1.56 ÷ 2 = 0.78
0.78 ÷ 2 = 0.39
0.39 ÷ 2 = 0.20
0.20 ÷ 2 = 0.10
0.10 ÷ 2 = 0.05
0.05 ÷ 2 = 0.02
0.02 ÷ 2 = 0.01
0.01 ÷ 2 = 0.01 (still rounding up)
0.01 ÷ 2 = 0.00
Now, our current value is at $0.00