One absent-minded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he travelled on foot to his friend's place a few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

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?

An office is divided into 8 cubicles. How many of the cubicles are painted if only 1/8 of the cubicles are painted?

A woman named Maria was at the funeral of her mother. She met a nice young man that she had never seen before and after the service, they spent a bit of time together. Then she got busy and didn’t get his name or phone number before he left. She tried to find him, but no one knew who he was or how to contact him. A few weeks later, Maria’s older sister dies and the police suspect murder. Who killed the sister?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

If you paint a brown house white it will become a white house. If the stoplight changes from red to green, then the light is green. So, if you throw a white shirt into the Red Sea, what will it become?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?