Learning About the Doubling Effect

Back in the 1970s, a commercial made reference to a shampoo and the girl who tried the shampoo told two friends, who in turn told to more friends the next day and they also told two friends etc. The doubling effect is powerful when it's gossip, lies and even handy to determine how many times you'll need to rip a paper in half to come up with a certain number of pieces.

Now, how many people would know about the shampoo on the 10th day? The 20th day? How long before a million people would know? Here's a PDF Worksheet, see how well you do. (See next for help with developing a strategy.)