What does this rebus riddle means ?

Write the next letter in this sequence.
O, T, T, F, F, S, S, E, __
**Hint: It is a Number Series Puzzle

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

Can you count the number of matches in the picture below ?

If six children and two dogs were under an umbrella, how come none of them got wet?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see? What is it?

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

Decode below rebus
D
N
A
T
S , D

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.