Power of Compounding : Rice grains can bankrupt an entire kingdom

There was once a poet who came to king in search of some help. He sang his poems in forng of the King and King liked it very much.

King : I am very happy with you. Ask whatever you want as a reward.

Poet : My Lord, I just want rice grains for the next 64 days.

King : (Little confused) I am ready to give you gold and land but you are asking for something as cheap as rice ?

Poet : Yes my king. Today I will take one single grain of rice. Tomorrow I will take 2 grains of rice. On the 3rd day I will take 4 grains of rice. I will just take the number of rice grains just twice of what I took the previous day. I will continue to come for next 64 days like this.

King: (Laughs aloud) You are so silly. You just want to take rice grains for 64 days and that too just a single rice grain today. I promise to fulfil your wish.

Thinking of such a silly wish the king promised to fulfil it in-front of the whole palace. The king was a man of principles. He always kept his promises in the past.

So the poor poet comes takes rice grains everyday starting with just a single rice grain on that day.

Day 0 : 1 rice grain

Day 1 : 2 rice grains

Day 2 : 4 rice grains

Day 3 : 8 rice grains

Day 4 : 16 rice grains

Day 5 : 32 rice grains

Day 6 : 64 rice grains

Day 7 : 128 rice grains

Day 8 : 256 rice grains

Day 9 : 512 rice grains

Day 10 : 1024 rice grains



Day 32 : 4,294,967,296 rice grains



Day 64 : 18,446,744,073,709,551,616 rice grains

  • In words :
    • “Eighteen quintillion, four hundred and forty-six quadrillion, seven hundred and forty four trillion, seventy three billion, seven hundred and nine million, five hundred and fifty one thousand, six hundred and sixteen” rice grains.

I tried to convert that into tonnes by taking weight of 1 rice grain =0.03 grams

  • It comes out to be approx 553 402 322 211 tonnes of rice i.e
    • “Five hundred fifty-three billion four hundred two million three hundred twenty-two thousand two hundred eleven” tonnes of rice. Not even kilos.
  • Just for a comparison :
    • “The Global annual rice produced at present is only 700 million tons”

The king sold his entire kingdom day by day but still could not fulfil the demand of 64 days. He asked for forgiveness. The poet forgives him and says :

“Think before you promise anything. Few things sounds extremely wrong and silly at first, but they are actually correct and beyond our imagination”

It was just a story used to explain the effect of a well known problem called “Wheat and the Chessboard Problem.

Image source : Google

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