Can you arrange the six given marbles in a manner that each one of them is touching all four marbles of different colours?

You can move only two matchsticks in the given picture. What is the highest number you can form by doing it?

Can you count the number of squares in the figure below?

Can you count the number of rectangles on a chessboard?

Find the missing number in the sequence.

3 5/3 7/5 11/7 ? 17/11