What brings you down but never up?

Find the next number in the series below

21 32 54 87 131 ?

Can you replace the question mark with the correct number?

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

What is the next number in this matchsticks series riddle?

Who is that with a neck and no head, two arms and no hands? What is it?

There are nine dots in the picture that has been attached with this question. Can you join all the dots by drawing four straight lines without picking up your pen?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?