Can you count the number of triangles in the picture below?

When we see 2 but call 10?

Which tank will fill first?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

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

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

Three friends decide to distribute the soda cans they had among them. When all of them had drunk four cans each, the total number of cans that remained was equal to the cans each one of them had after they had divided the cans.

Can you calculate the total number of cans before distribution?

Forwards I am heavy, backward I am not. What am I?

What type of tree can I carry in my hand?