I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

As shown in the image, the nine Dogs are square fenced. By constructing just two square fences can you make sure that two Dogs cannot meet each other without crossing the fence?

What has one eye, but can’t see?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?