What goes up but never comes down?

Can you name some countries which do not have the alphabet 'A' in them?

I am a ten letters word
The first four letters have the power to rule,
Next, four-letter can be eaten.
The next three-letter represents a lady.
I can fly as well

what am I looking for?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

Some friends went on a vacation to a resort. It was raining heavily and it kept raining for thirteen days.

When it rained in the morning, the afternoon was beautiful and when it rained in the afternoon, the day was blessed with a clear morning.

Overall, the friends experienced eleven nice mornings and twelve nice afternoons. Can you find out the number of days they spent on vacation?

Three ants are sitting at the three corners of an equilateral triangle. Each ant starts randomly picks a direction and starts to move along the edge of the triangle. What is the probability that none of the ants collide?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

Which digit occurred maximum times between the number 1 and 1000?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?