What is the next number in this matchsticks series riddle?

The King of a distant land had heard that Birbal was one of the wisest men in the East and so desired to meet Birbal. He sent Birbal an invitation to visit his country.

In due course, Birbal arrived in the distant kingdom. When he entered the palace he was flabbergasted to find not one but six kings seated there. All looked alike. All were dressed in kingly robes. Who was the real king?

The very next moment he got his answer. Confidently, he approached the king and bowed to him.

How did Birbal know who was the real king?

The sum of a mother, her baby and her dog's weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

What is the largest number you can write with just 3 digits?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

A man dies of old age on his 25 birthday. How is this possible?

How is the moon similar to a dollar?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?