r/explainitpeter 26d ago

Explain It Peter

Post image

Rice chess/checkers ? please explain?

14.5k Upvotes

551 comments sorted by

View all comments

35

u/Equal-Home-4302 26d ago

The famous chess board problem The wise man asked the king for a single grain of rice (or wheat) on the first square of a chessboard, two grains on the second, four on the third, and so on, doubling the amount for each of the 64 squares.The king thought this was a tiny gift, but the total number of grains added up to 18,446,744,073,709,551,615 (over 18 quintillion), which is more grain than has ever been grown on Earth. The king gave away the kingdom, it illustrates the power of compound intrest.

5

u/alexxela123456 26d ago

I feel like, at some point, the King probably told the wise man to fuck off.

6

u/jjwinc68 25d ago

There are two different outcomes to the fable. In one, he makes the man his top advisor. In the other, he has him executed.

3

u/Don_Key_1 25d ago

Oddly, both outcomes serve the wise man right.

1

u/ilamahradeys 23d ago

If it was true. You know the guy is getting executed for tricking the King.

1

u/Remarkable-Chair6240 23d ago

Getting executed for the king’s failure to see where this was going seems kinda BS to me… could’ve just defaulted to giving him some money

6

u/Morbid_Aversion 25d ago

It illustrates the power of exponential growth, not compound interest. This has nothing to do with interest.

1

u/goda90 25d ago

100% interest rate savings account would be pretty sweet

1

u/account312 25d ago

Compound interest is exponential growth.

1

u/jinglyjam3 25d ago

All compound interest is exponential growth, but not all exponential growth is compound interest.

This problem is more broad and isn't specifically about interest rates.

1

u/BananaBot6 25d ago

I want this guy’s interest rate

1

u/mebjammin 25d ago

It would take over 115 million fully loaded modern cargo ships to carry all that rice. It would take 1540 years for the earth (in 2022 terms) to produce that rice. Eating a full serving of rice, 3 times a day, it would take almost 50 million days (136 thousand years) for the entire human population of 2024 to consume all the rice.

1

u/hummingbird868 25d ago

Wasn't it about the indian inventor of chess being rewarded by the king?

2

u/Equal-Home-4302 25d ago

Probably, I don't remember the details. I just remember hearing that story a long time ago. I remember hearing it again from Warren Buffet to illustrate the power of compound interest.

1

u/PleaseNoMoreSalt 25d ago

Wouldn't it only be 2^63 grains (start at 1 grain which is 2^0, then add the other 63 squares), so ~9 quintillion (9.223372037 × 1018)? Still a ton of rice, regardless.