If it took eight men ten hours to build a wall, how long would it take four men to build it?

There was a minor accident with a doctor's son but the doctor noticed no major injury. After the treatment, the father of that doctors son is sitting with the son of the doctor without the doctor being in the room.

How can this be possible?

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

A newspaper is supposed to have 60 pages, but pages 24 and 41 are missing.
Which other pages won't be there?

Count the number of squares in the picture below.

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

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

I have a big mouth and I am also quite loud! I am NOT a gossip but I do get involved with everyone's dirty business.

In a science lab, a petri dish hosts a healthy colony of yeast for an experiment. Now every minute, all the yeast cells divide into two. At noon, there was just a single cell of yeast and at 1:22, the Petri dish was half full. Can you calculate when the dish will be full of yeast?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?