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

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

I’m tall when I’m young, and I’m short when I’m old. What am I?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

Can you write down eight eights so that they add up to one thousand?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

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

Nodes are shown below and you need to connect them based on the following rule: Every node can be connected to the number of nodes inside them, i.e. the first node there is a value of 1 which indicates that the first node can connect to exactly one node only.Can you do it?

Can you solve below mathematical equation?

2^1234 - 2^1233

There is a wide field of corn. A goose finds its way into the field and starts running. Can you find out till which point the goose can run into the field?