This little riddle is written by the Indian mathematician Bhaskara(1114-1185), in his book Lilivati.
Originally he wrote it to give his keep his daughter occupied with(rather than an unhealthy love-affair)
Out of a flock of geese, ten times the square-root [of the total] went to the Manasa lake when a cloud approached,
one-eighth went to a forest filled with hibiscus,
and three couples were seen playing in the water.
Tell me, maiden, the number of the flock.
It's not perhaps the hardest riddle, but it's a neat one. Also you can easily get stuck if you don't read it correctly, or if you try to think overly-complex!
PS: Don't spoil the fun for everyone else by blurting out the answer. If none has understood it in a week or so, I'll post an explanation