I am white when I am dirty, and black when I am clean. What am I?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Why 1729 is a magic number? Answer Logically.

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

What is the next number in this series?

4,12,84,3612....

What does the below rebus riddle means?

John can place six large boxes or nine small boxes into a carton.

Can you find out in how many cartons can he place sixty-six boxes in total?

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?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?