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

What does this below rebus puzzle mean?

John is 45 years older than his son Jacob. If you find similarities between their ages, both of their ages contain prime numbers as the digits. Also, John's age is the reverse of Jacob's age.

Can you find their ages?

If one and a half boys, eat one and a half burgers in one and a half hours.

How many burgers can 9 boys eat in 3 hours?

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

As shown in the image, the nine Dogs are square fenced. By constructing just two square fences can you make sure that two Dogs cannot meet each other without crossing the fence?

A man is found hanging dead from the ceiling of a room. The room’s dimensions are 15 x 15 x 15. The man is only 6ft tall and the rope was only 2ft long. There are no windows and only one door to the room. The door is bolted shut from the inside, and a puddle of water is under the man. How did he kill himself?

Can you tell a 3D object that has just two surfaces?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.