Practice Room · Things that double every day

Practice: Doubling

For each question, give a low and a high you are 80% sure the answer sits between. Tighter brackets score more; a miss scores zero. You can type 2 million, 3e9, 1.5k or 45%.

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DoublingQuestion 1 of 5

There is 1 grain of rice on day 1, and the number doubles every day (2 on day 2, 4 on day 3). How many grains are there on day 18?

Low High grains

DoublingQuestion 2 of 5

There is 1 paper clip on day 1, and the number doubles every day (2 on day 2, 4 on day 3). How many paper clips are there on day 30?

Low High paper clips

DoublingQuestion 3 of 5

There is 1 paper clip on day 1, and the number doubles every day (2 on day 2, 4 on day 3). How many paper clips are there on day 31?

Low High paper clips

DoublingQuestion 4 of 5

There is 1 grain of rice on day 1, and the number doubles every day (2 on day 2, 4 on day 3). How many grains are there on day 37?

Low High grains

DoublingQuestion 5 of 5

There is 1 grain of rice on day 1, and the number doubles every day (2 on day 2, 4 on day 3). How many grains are there on day 20?

Low High grains

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