What is black when you buy it, red when you use it, and gray when you throw it away?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

Only one color, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

John is pretty weird. He likes toffees but hates chocolates. He loves books but never reads. He likes to build his troops in an online game but does not proceed with the war. He likes to go swimming but is afraid of water.

Seeking this behaviour, can you tell whether he likes balloons and parties?

Can you discover the missing number in this series?

37, 10, 82
29, 11, 47
96, 15, 87
42, ?, 15

There are forty elephants and they have forty-fore heads. How can this be possible?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

A Man gave one of his sons 10 cents and another son was given 15 cents. What time is it?
Hint: Figure out the relation between time and number, is not so easy..:)

What has a ring but no finger?