Prove that the below maths equation is true.

8 + 8 = 91

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

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

It can't be seen, can't be felt, can't be heard, and can't be smelt.
It lies behind stars and under hills, And empty holes it fills.
It comes first and follows after, Ends life, and kills laughter.
What is it?

How can you take 2 from 5 and leave 4?

Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

Can you solve below mathematical equation?

2^1234 - 2^1233

A time long back, there lived a king who ruled the great kingdom of Trojan House. As a part of the renovation of the kingdom to meet future security needs, he asked his chief architect to lay down a new play in a manner that all of his 10 castles are connected through five straight walls and each wall must connect four castles together. He also asked the architect that at least one of his castles should be protected with walls. The architect could not come up with any solution that served all of King's choices, but he suggested the best plan that you can see in the picture below. Can you find a better solution to serve the king's demand?

Where do fish keep their money?