What happened when the wheel was invented?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

A dying old man wants to divide his entire land between his only two sons. Since his only wish is to treat them as equal as both of them have been too good to him, he wants to divide his land equally between them. The problem is that the land is significantly irregular in shape and thus there is no choice of cutting them into two equal halves.

Can you help him divide the land in a manner that both of his sons will be happy?

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?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

What month of the year has 28 days?

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?