Throw ten coins onto a flat surface. Move aside all the coins that landed tails-up. Collect the remaining coins. After tossing them once again, remove all coins that landed tails-up. Repeat this process until all the coins have been removed. Can you see how this is related to radioactive half-life? In units of “tosses,” what is the average half-life of 25 coins? 50 coins? 1 million coins?