What has no start, end, or centre?

In the figure that has been attached to this question, each digit represents a digit. The similar letters carry the same integer value. Can you expose the original digits?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

The Little ant seems to be always confused. Do you know why?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

How many triangles can you count in the figure given?

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

What has to be broken before you can use it?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?