What has many keys but can’t open a single lock?

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?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

You Throw The Outside, Cook The Inside
Eat The Outside, Throw The Inside.

What Is It?

If 2 workers can complete painting 2 walls in exactly 2 hours.

How many workers would be needed to paint 18 walls in 6 hours?

In the image below, can you find the value of an angle(y)

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

If eleven plus two equals one, what does nine plus five equal?

What's a single-digit number with no value?

What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 1000?