Replace the question mark with the correct number below.

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

In a football game, Christina defeated Teresa by 2 - 0 but no man from either side scored. How can this be possible?

When we see 2 but call 10?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

Why is 6 afraid of 7?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different. How do you measure 45 minutes?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

What English word has three consecutive double letters?