Complete the table series riddle by finding the number that can replace "??".

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?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

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?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

A frog is at the bottom of a 30-meter well. Each day he summons enough energy for one 3-meter leap up the well. Exhausted, he then hangs there for the rest of the day. At night, while he is asleep, he slips 2 meters backwards. How many days does it take him to escape from the well?

How can you take 2 from 5 and leave 4?