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

I have two coins.
* One of the coins is a faulty coin having a tail on both sides of it.
* The other coin is a perfect coin (heads on side and tail on other).

I blindfold myself and pick a coin and put the coin on the table. The face of the coin towards the sky is the tail.

What is the probability that another side is also tail?

John went to buy some expensive, foreign chocolates. He only had Rs 100 with him. When he reached the shop, he got out and know that on those chocolates, there was a 15% import duty and 5% VAT.

How much worth chocolate should he buy so that he can accommodate it in Rs 100?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

If 21x = 79x, what is the value of x?

If "P" means "-", "Q" means "/", "R" means "+", and "S" means "*" then find the value of the following:

21 Q 7 R 9 S 10 P 13

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

Rectify the following equality 101 - 102 = 1 by moving just one digit.

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?