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Complete the missing letters of the given word.

What is the Surname of Barbie Doll?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

The dirtier I get, the whiter I look. Who am I?

He digs out tiny caves and stores gold and silver in them. He also built bridges of silver and made crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs his help, yet many people are afraid to let him help them. Who is he?

Can you solve this picture maths equation?

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

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?