Replace the question mark with the correct number in the below-given picture?

How can you take 2 from 5 and leave 4?

What's the only room from which no one can enter or leave

Count the number of triangles in the given picture.

What kind of band never plays music?

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

What is the Surname of Barbie Doll?

I cannot talk, but I always reply when spoken to. What am I?

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?