Can you convert the number zero(0) into a positive number using just one mathematical operator ?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

Take away the whole and some still remain. What is it?

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?