Get 100 pennies. Think of them as a new radioactive isotope. We will call it Coinium isotope. One coin "decays" when it comes up tails. Start with all your 100 coins by tossing them on the floor or a large table. Remove the coins that decayed (tails). Toss the remainder and remove the ones that decayed and so forth.

On an Excel sheet (or other programs), make a table of the number of remaining coins versus the number of years (throws/tosses). Make a plot of the data points, where the horizontal axis represents the number of years (number of throws) and the vertical axis represents the remaining coins. Continue plotting your points until your sample decays to zero. Connect the points in a smooth curve that runs evenly between the points (but not necessarily touches all the points (see sample plot provided). Excel should be able to take care of that.)