Puzzles - Number puzzles

Answer

:

2

Explanation

:

The sum of the 4 digits at the corners of the diagram is 17, as is the sum of the 4 digits in the middle of each side of the diagram.

Answer

:

9

Explanation

:

Starting with the top left square, and moving clockwise around the other 3, the sum of the digits in each square follows the sequence 20, 19, 18, 17.

Answer

:

71

Explanation

:

As you move clockwise around the diagram, add the previous 2 numbers together and subtract 3 to give the next number in the chain.