Find the next number in the sequence

1, 2, 6, 21, 88, __?

Find out which of the given views in the picture is accurately the top view of the given pyramid.

Forwards I am heavy, backward I am not. What am I?

What has 88 keys?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

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?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

Lifeless eyes on my smiling face and watch your child's sleeping place. In their dreams they hold me tight. What am I?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?