There is a lake in which every day some new lotus flowers grow. Their growth follows a pattern; if on a given day there are X flowers, then on the next day there will be 2X flowers will be there. So everyday the number of flowers gets doubled.

Now the main question is:

If the whole lake gets covered with lotus flowers in 13 days, then how many days does it take to cover only 1/32th part of the lake?

  • $\begingroup$ Question makes no sense: it's either 1/32th, or 32%, the two are not equivalent. $\endgroup$ Commented Oct 7, 2014 at 6:45
  • 5
    $\begingroup$ When asked like this, it's a straight forward calculation, and not a very interesting one at that. The way I've heard this puzzle before, is something along the lines of "on the first day there is one flower, on the second day there are two, on the third day there are four, on the fourth day there are eight and so on. If it takes 65 days for half the lake to be covered, how many days before the entire lake is covered?", which adds the difficulty of having to realise that the number of flowers doubles every day, which makes it take just one additional day for the lake to be covered entirely. $\endgroup$
    – SQB
    Commented Oct 7, 2014 at 7:09
  • $\begingroup$ "1/32nd" is the correct ordinal. $\endgroup$
    – zzzzBov
    Commented Oct 7, 2014 at 17:52

1 Answer 1


Assuming you mean 1/32th:

It should take 8 days.

On day 9 you'll have 1/16th
On day 10 you'll have 1/8th
On day 11 you'll have 1/4th
On day 12 you'll have 1/2nd
On day 13 you'll have a full lake.


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