O_er_t_o_

Complete the missing letters of the given word.

Prove that the below maths equation is true.

8 + 8 = 91

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

What has no start, end, or centre?

You need to pick one entry from pot A and one from pot B to have a perfect match. Can you do it?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

What word is pronounced the same if you take away four of its five letters?

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

What does the below mathematical rebus mean?

By using all numbers, i.e. 123456789 and subtraction/addition, operators number 100 can be formed in many ways.
Example: 98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100

But if we add a condition use of the number 32 is a must. Then there are limited solutions.
One of such solution is: 9 - 8 + 76 + 54 - 32 + 1 = 100

Can you tell me any other solution?