In the lake, lotuses grow. Over the course of a day, each lotus splits in half, and instead of one lotus, two appear. After another day, each of the resulting lotuses splits in half, and so on. After 30 days, the lake is completely covered with lotuses. How long did it take for the lake to be half full?

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Note that the number of lotus flowers doubles in one day.

## Solution

If you read the condition of the problem carefully, you will understand that the lake was half full after 29 days. The day before the lake is completely filled, it will be exactly half full.

## Answer

After 29 days