Logical puzzles

Adding the three numbers in each square together gives the numerical value of the letter at the centre of each square.

The value at each corner of the diagram equals the difference between the sums of the numerical values of the letters in the boxes adjacent to the corner.

In each diagram, the numerical value of the left hand letter equals the product of the upper and lower left hand numbers, and the right hand letter equals the product of the upper and lower right hand numbers. The numerical value of the central letter equals the sum of the numerical values of the left and right hand letters.

Start in the top left hand corner and move anti clockwise around the perimeter of the square. Letters are written in alphabetical order, skipping 1 letter, then 2 letters, then 3 etc.

In each row, multiply the numerical values of the left and right hand letters, putting the result in the centre.

In each diagram, convert each letter to its numerical value, and read the top and bottom pairs of letters as complete 2 digit values. Multiply these values together to give the 3 digit result written in the centre spaces.

In each row, the left hand number equals the total of the even valued letters in the middle box, and the right hand number equals the total of the odd valued letters in the middle box.

In each row, add together the numerical values of the 3 central letters to give a 2 digit sum, and put this 2 digit sum in the left and right hand boxes at the end of the rows.

Working in rows, add the left and right hand numbers together, and put the letter with the reverse alphabetical value of this sum in the central box.

Splitting the diagram in half both horizontally and vertically, each quarter contains a pattern of black squares, representing the letters W, X, Y and Z.