What does it mean?

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

Replace the question mark with the correct number in the below-given picture?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

At a bar, three friends, Mr Green, Mr Red and Mr Blue, were having a drink. One man was wearing a red suit; one a green suit; and the other a blue suit. 'Have you noticed,' said the man in the blue suit, 'that although our suits have colours corresponding to our names, not one of us is wearing a suit that matches our own names?' Mr Red looked at the other two and said, 'You're absolutely correct. What colour suit is each man wearing?

What does the below image rebus riddle means ?

Can you place six X (crosses) in below board without making three in a row in any way ?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

What can jump higher than a building?