In 2014 I had the opportunity to present my book “Pocket Money Management” during a book presentation in my hometown on a nice warm and sunny summer day. It was a public place and the audience consisted mostly of students. In such gatherings I always try to make the presentation a little entertaining, so I promised to reward the person who presents first the result for the following task with a big ice cream.
The story goes like this:
The Chinese emperor’s daughter was ill, and the emperor promised immeasurable riches to anyone who could cure her. A young traveler named Pong Lo came to the palace. With his intelligence and knowledge, he nursed the princess back to health and won her heart. For his reward, Pong Lo asked for the daughter’s hand in marriage. The emperor rejected this proposal and told Pong Lo to ask for something else – anything he wanted
After a few moments of deliberating, Pong Lo said: “I want a grain of rice.”
“A grain of rice? What nonsense! Ask me for fine silk, the largest room in the palace, or an entire zoo full of wild animals – anything can be yours!”
“A grain of rice will do”, said Pong Lo. “But if you insist, your majesty, you may double the number of grains of rice every day for the next fifty days.”
The emperor agreed. And so it was that on the first day, Pong Lo received one grain of rice, on the second day he received two, on the third day it was four grains, and so on.
In the book presentation the task for the students was to double the number of grains of rice 20 times.
Amazingly a few minutes later a elderly woman showed up, held a small paper in her hands and said “I have the solution!” Surprised I checked the result and it was right. I asked her how you came to this result so fast. I just calculated in my head and checked the numbers with a pencil and a paper. I asked her “May I ask you how old you are?” “78” was her sound answer.
You can read the whole story in my book “Pocket Money Management” and also the not so happy ending for the too smart Pong Lo.