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In this question there is a black triangle, a medium grey triangle and a light grey triangle each of which follows its own rule.
The black triangle rotates around the octagon by 135? clockwise each time.
The medium grey triangle rotates by 180? each time.
The light grey triangle rotates by 90? anticlockwise each time.
Following these rules, the correct answer is D.

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In this question there are three rules to follow that must be applied simultaneously:
The whole shape is rotated by 72? anticlockwise each time.
The number of dots in the circle which starts in the 9 o’clock position increases by one each time.
The number of dots in the circle which starts in the 3 o’clock position decreases by one each time.
When all these rules are applied together, the correct answer for the missing diagram of the sequence is B.

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In this question there are two rules to follow that are applied alternately.
The first rule is that the spiral is reflected in the diagonal shown.
The second rule is that the spiral rotates by 90? clockwise.
To obtain the next diagram of the sequence, the first rule should be applied next and the correct answer is A.

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In this question the dot rotates around the perimeter of the regular hexagon, always rotating in the direction indicated by the arrow.
The numbers of places it rotates are: 1 the first time, 2 the second time, 3 the third time etc.
To obtain the next diagram of the sequence, therefore, the dot should rotate 5 places in the direction indicated by the arrow, which is clockwise.

The correct answer is C.

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In this question the three shapes - equilateral triangle, square and regular pentagon - rotate by 90? clockwise around the four positions of the grid. At the same time, each shape also rotates about its own centre.
The equilateral triangle rotates by 120? anticlockwise each time.
The square rotates by 90? anticlockwise each time.
The regular pentagon rotates by 72? clockwise each time.
When all these rotations are applied simultaneously, the next diagram of the sequence must be B.