Why Aeroplane windows are round?

Can you name some countries which do not have the alphabet 'A' in them?

Count the number of triangles in the given picture.

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

What is the word or phrase?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

Why do you find that most of the buildings are deprived of the 13th floor?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

In an Art Gallary, When the clock hit 11 am, Artist hung the painting number 30. When it struck 4 pm, he hung painting number 240 and when it struck 7:30 pm, he hung painting number 315.

Can you determine, which painting number will he hang when the time is 9:20 pm?

Find the combined weight of the Cat, Dog and Rabbit in the given picture.