The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

Count the squares in the matchstick puzzle below?

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

A mother bought three dress for her triplets daughters(one for each) and put the dresses in the dark. One by one the girls come and pick a dress.
What is the probability that no girl will choose her own dress?

What work can one never finish?

John and his team plan to rob a safe. They got just one chance to break the code else the local police will be informed. Below are clues:
A) Exactly one number is perfectly placed: 9 8 1
B) Everything is incorrect: 9 2 4
C) Two numbers are part of the code of the safe but are wrongly placed: 0 9 3
D) One number is part of the code of the safe but is wrongly placed: 1 4 7
E) One number is part of the code of the safe but is wrongly placed: 7 8 3

Seven Robbers robbed a bank and hide the coins in a lonely place.
They decide to divide the money equally the next morning. Two greedy robbers decided to cheat the others and reach the place at night. They equally divided the coins between them, one coin left. So they called another robber and then they decided to divide equally among the three. Sadly again one coin left. The same thing happened to the 4th 5th and the 6th robber.
However, when the 7th robber reached in the morning, they can divide the coins equally.

How many coins were there in total?