To calculate the half-life of an element based on trials with dice, we need more context about how the trials are structured. In general, the concept of half-life is the time required for a quantity to reduce to half its initial amount.
If you're simulating decay with dice (for example, rolling 12-sided dice and considering some faces to represent the stable or unstable isotopes), the actual half-life would depend on how you define a successful decay event in your experiment.
Assuming you are rolling dice, if you decide that a certain face represents "decay" (for example, rolling a specific number like a 1), you would count how many dice show that face, and each trial of rolling the dice would agree on what constitutes decay.
If you can provide more specifics about how you are conducting the trials or determining decay, I can assist you in calculating the half-life based on those parameters!