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

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

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?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

What is the Surname of Barbie Doll?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

Can you solve the below tricky visual equation?

Replace the question mark in the picture below.

Which five letter word can be added at the end of below word to form a
valid word?

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