Puzzles - Number puzzles

Answer

:

6

Explanation

:

On each row, add the values of the left hand and central boxes to give the value in the right hand box.

Answer

:

10

Explanation

:

In each star diagram, the number in the centre equals the sum of the top three numbers, subtracting the sum of the bottom two numbers.

Answer

:

23

Explanation

:

Starting top left, and moving down in columns from left to right, the numbers follow the sequence of Prime Numbers from 2 to 23.