what does this picture(rebus) riddle means ?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

Can you count the number of children in the picture below

I am the beginning of everything, the end of everywhere. I'm the beginning of eternity, the end of time and space. What am I?

Why 1729 is a magic number? Answer Logically.

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

Rose, Lily and Jasmine decided to buy flowers for their moms on Mother's Day. One of them bought lilies, the other roses, and the third one jasmines.
'It's funny!' said the girl with roses, 'we bought roses, jasmines and lilies, but none of us bought the flowers matching her name'.
'You're right!', said Lily.
What kind of flowers did each of the girls buy?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?