Compound interest explained clearly: The story of the king, the chessboard and the grain of rice

Once upon a time there was a clever man who had invented the game of chess. His king wanted to reward him for this invention and told him to may express a wish. The wise man, however, desired neither riches nor fame. He only asked for a simple chessboard and a basket full of rice grains. The king, confused and curious at the same time, agreed.

The wise man revealed his plan: He began to fill the chessboard with grains of rice. He placed a single grain of rice on the first square, two grains of rice on the second square, four grains of rice on the third square and so on. The king, who did not realise the implications of this wish, thought the proposal was unspectacular and agreed.

With each field on the chessboard doubled the wise man the number of grains of rice.

While the rice grains were only a modest amount in the first fields, they began to Grow exponentially on the later fields.

Small quantities quickly become the quantity of a whole sack full of rice.

At Field 30 arrived, we are already talking about Thousands of (modern) freight wagons from trainswhich can load 75 tonnes of rice.

And with the amount of rice from Chessboard number 40 can already be seen in the Canton of Zurich and a small part of the Aargau Cover with rice.

Afterwards the Growth so unimaginably greatthat it completely exceeds our imagination (if it hasn't already). Now we can fill so many railway wagons (each loaded with 75 tonnes) with rice and string them together that we can Generate a train that reaches a thousand times around the equator!

So much rice logically exceeds all the productions in the world and the king in the story could therefore not fulfil his promise.