What is the next number in this matchsticks series riddle?

Give it food and it will live; give it water and it will die.

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

What is the fastest way to double your money?

Which number should replace the question mark?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

Astrology starts with the alphabet A, Biology starts with B, Psychology with P and Limnology with L.

Can you find an "ology" that begins with a P?

When I asked a girl's name she told me her name is the date '07/09/2001'.

I thought for a few seconds and then I got her name. Do you?

I have Rs.50 and I spend it in the way as below.

what does this picture(rebus) riddle means ?