Can you find out which number multiplied by itself will give the output as 12345678987654321?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

Spot 5 differences in two Christmas tree below:

This is a simple one. You just have to count the number of Fs in the given sentence.

Finished Files are the result of years of scientific study combined with the experience of years.

How many did you count?

Before Mount Everest was discovered, what was the highest mountain in the world?

Can you find out the total number of triangles in the given figure?

With the help clues provided in the image, can you find the 5 digit key?

500 women soldiers are arranged in an array of ten rows and fifty columns in accordance with their respective heights. Now, the tallest woman from each row is asked to move out in the front. From them, the shortest one is labelled as Alpha. They are then asked to resume their original position.

Now, the shortest woman in each column is asked to come out in front. The tallest among them is labelled as Beta.

Can you find out if Alpha will be taller or Beta?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

The picture shows the dice results in each couple of throws. If they are actually following a pattern, can you find out the missing one?