Starting with the top letter in each star, and moving clockwise around the others, letters advance through the alphabet in steps of 8 for the left hand star, 9 for the right hand star, and 10 for the central star.

The sum of the letters in the three adjacent circles on each side of the diagram is always 30.

The diagram contains 3 sets of 4 letters - one set of outer corner letters, one set of inner corner letters, and one set of letters on each side of the square. The numerical values of the letters in each set add up to 40.

In each diagram, the central letter falls midway between the left and right hand letters, and the top and bottom letters.

Start on the upper left of each diagram, and move to the right, then down the last 2 boxes in the centre. Letters are written in alphabetical order, in steps of 5 for the left hand diagram, 6 for the next, then 7, then 8.

Starting with the left hand circle in the top row, add 4 to the numerical value of each letter and write the letter with this value in the corresponding segment of the lower left circle. Continue this pattern, adding 5 to the letter values in the central circle, and 6 in the right hand circle.

Start with the C at the centre of the diagram and follow 2 sequences of letters, both clockwise from the C, one around the upper half of the diagram, and one around the lower half. Letters in the upper half advance through the alphabet in steps of 7 letters at a time, and letters in the lower half advance in steps of 9.

Start at the top left of the diagram, and work down the left hand column, then along one space to the right and up the next column, in a snakes and ladders pattern, write the following repeated sequence of letters: A C P R F D U

Convert each letter to its numerical value, and read horizontal lines as 2 or 3 digit numbers. Add the top 3 digit number to the 2 digit number below to give 200, repeat this pattern for the 3 and 4 digit numbers underneath.

Start on the top left of the diagram and work from top to bottom in columns, from left to right. Letters are written in alphabetic order, in a repeated sequence of steps of 5, 6 and 7.

Starting at the top left of the diagram, and moving around it in a Z shape, letters follow the alphabetic sequence, in steps of 6 letters at a time.

Treat each star as 2 intersecting triangles, and start on the top or the left of each triangle in each star and move clockwise around it. Letters are written in alphabetical order in steps of 6 for the left hand star, 7 for the right hand star and 8 for the central one.

Working in rows, the numerical value of the letter in the right hand column equals the sum of the numerical values of the letters in the left and central columns.

In each row, the value in the centre equals the difference between the sum of the numerical values of the pair of letters to the left and the pair of letters to the right.

Split the diagram into 3 rows, each 2 boxes high. In the top double row, letters are written in sequence, from left to right, alternating between the upper and lower row, in steps of 6 letters at a time. The middle row follows the same sequence, in steps of 7 letters at a time, as does the bottom row, in steps of 8 letters.

Start with the top left hand segment of the top left hand square, and move around the other squares in a clockwise direction. Letters are written in sequence in steps of 5 letters at a time for the top left segment, 6 letters for the top right, 7 for the bottom right and 8 for the bottom left. The relative positions of the letters in each sequence move 1 segment clockwise at every step.

In each circle, the numerical value of the letter in the lower left quarter equals the sum of the numerical values of the upper 2 letters, and the numerical value of the letter in the lower right quarter equals the difference between the numerical values of the upper 2 letters.

Starting with the top left segment of each circle, and moving clockwise, letters follow the alphabetic sequence, in steps of 3 letters for the top circle, 4 letters for the left hand circle, and 5 letters for the bottom circle.

Start at the top of the diagram, and work through each row from left to right. Letters move through the alphabet, In steps of 3 letters, then 4, 5 and 6, repeating this sequence.

In each diagram, starting on the top left and moving clockwise in a spiral towards the centre, letters increase in value by 3 for the left hand diagram, 4 for the middle, and 5 for the right hand diagram.

Split the circle into 4 quarters, horizontally and vertically, with 2 segments each. Starting with the top left segment, the sum of the numerical values of the letters in the 2 segments equals 15. The sum of the next pair of segments clockwise equals 16, then 17, then 18.

Start on the top left of the diagram, and move clockwise in a spiral towards the centre. Letters advance through the alphabet in steps of 5.

In each column of the diagram, the sum of the numerical values of the letters is always 25. So, I + M + B + ? = 25 9 + 13 + 2 + ? = 25 / = 25 - 24 = 1. Missing Character = 1 = A.

Start at the top left, and work through the diagram in a Z shape, letters move through the alphabet in steps of 6, then 7, then 8 etc.

Starting with the B on the lower right of the triangle, and following the diagram round in a clockwise direction, letters move through the alphabet in steps of 5.

In each square, start with the left hand segment, and move clockwise around the others. Letters are written in alphabetical order in steps of 10 for the top left square, 11 for the top right, 12 for the lower left and 13 for the lower right.

Taking each pair of letters in each row, the numerical value of one letter equals the inverse numerical value of the other letter.

In each group of 3 squares, starting on the upper left and moving clockwise around the other 2 squares, letters follow the alphabetic sequence in steps of 6 for the left hand diagram, 7 for the upper middle, 8 for the right hand diagram and 9 for the lower one. So, E + 9 = N N + 9 = W

Add 6 to the numerical value of each of the larger letters, and write the letter with this value in the smaller square diagonally opposite.

Converting each letter to its numerical value and reading each line as a 2 digit number, the numbers follow the sequence of multiples of 6, from 36 to 54.