What is the fastest way to double your money?

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

Replace the question mark with the correct number in below Picture:

What is always in front of you but can’t be seen?

Can you circle exactly four of these numbers such that the total is twelve?

1 6 1
6 1 6
1 6 1
6 1 6

There is a box. The area of its top is 240 square units, the area of the front is 300 square units and the area of the end is 180 square units.

Can you calculate the dimensions of this box with the given data?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

I have branches, but no fruit, trunk or leaves. What am I?

Can you count the number of squares in the given picture?

You’re out on the water and see a boat filled with people. You look away for a second and look back again, but this time you don’t see a single person on the boat. Why? Hint: The boat did not sink.