I am quite hot but become too cold if you remove the first two letters. What am I?

Can you fill the blank with the correct number?

6 30 870 756030 _____

I am a mother. However, I never give birth.

I am a father. However, I never nurse my children.

Wandering is not possible for me, but standing still happens occurs rarely.

Who am I?

Name a key which is hardest to turn.

You need to arrange three 7 and mathematical symbols to form number 1?

A father's child, a mother's child, yet no one's son.

Who am I?

What do you answer even though it never asks you questions?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?

Three people enter a room and have a green or blue hat placed on their heads. They cannot see their own hat but can see the other hats.
The colour of each hat is purely random. They could all be green, blue, or any combination of green and blue.
They need to guess their own hat colour by writing it on a piece of paper, or they can write 'pass'.
They cannot communicate with each other in any way once the game starts. But they can have a strategy meeting before the game.
If at least one of them guesses correctly they win $10,000 each, but if anyone guesses incorrectly they all get nothing.
What is the best strategy?