- Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
- A number between two cells indicates the sum of the numbers in these cells. A number between four cells indicates the sum between two diagonally adjacent cells, either top left + right bottom (\) or top right + bottom left (/).

- Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
- A number between two cells indicates the sum of the numbers in these cells. A number between four cells indicates the sum between two diagonally adjacent cells, either top left + right bottom (\) or top right + bottom left (/).

- Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
- The four corner boxes contain the same digit in symmetric positions about the centre.

- The four corner boxes contain the same digit in symmetric positions about the centre.

- If a shaded cell and a white cell are adjacent then the digit in the shaded cell is greater.

- If a shaded cell and a white cell are adjacent then the digit in the shaded cell is greater.

- A number in a squared cell indicates how many different numbers the four diagonally adjacent cells contain. A number in a circled cell indicates how many different numbers the eight orthogonally and diagonally adjacent cells contain.

- A number in a squared cell indicates how many different numbers the four diagonally adjacent cells contain. A number in a circled cell indicates how many different numbers the eight orthogonally and diagonally adjacent cells contain.

- Digits in adjacent cells cannot be consecutive.

- Digits in adjacent cells cannot be consecutive.

- Everywhere 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given. A checkerboard pattern is a 2x2 area of cells where the top-left and bottom-right cells are of one type and the top-right and bottom-left cells are of another type. All possible dots are marked.

- Everywhere 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given. A checkerboard pattern is a 2x2 area of cells where the top-left and bottom-right cells are of one type and the top-right and bottom-left cells are of another type. All possible dots are marked.

- A number between two cells indicates the quotient of the numbers in these cells. A number between four cells indicates the quotient between two diagonally adjacent cells, either top left + right bottom (\) or top right + bottom left (/).

- A number between two cells indicates the quotient of the numbers in these cells. A number between four cells indicates the quotient between two diagonally adjacent cells, either top left + right bottom (\) or top right + bottom left (/).

- There are some dots between cells. The numbers on each side of a dot must always be consecutive. Not all possible dots are marked.
- Digits outside the grid indicate the sum of the first 3 digits in the corresponding direction.

- There are some dots between cells. The numbers on each side of a dot must always be consecutive. Not all possible dots are marked.
- Digits outside the grid indicate the sum of the first 3 digits in the corresponding direction.

- The connected shaded cells contain each digit from 1 to 9.

- The connected shaded cells contain each digit from 1 to 9.

- Everywhere 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given. A checkerboard pattern is a 2x2 area of cells where the top-left and bottom-right cells are of one type and the top-right and bottom-left cells are of another type. All possible dots are marked.

- Each number at the intersection of four cells is the sum of digits in those four cells.

- Each number at the intersection of four cells is the sum of digits in those four cells.

- Some thermometer shapes are placed in the grid. Digits are strictly increasing from the round bulb of the thermometer to each flat end.

- Some thermometer shapes are placed in the grid. Digits are strictly increasing from the round bulb of the thermometer to each flat end.

- If absolute difference between two digits in neighbouring cells equals 1, then they are separated by a white dot. If the digit is a half of digit in the neighbouring cell, then they are separated by black dot. The dot between 1 and 2 can be either white or black.

- If absolute difference between two digits in neighbouring cells equals 1, then they are separated by a white dot. If the digit is a half of digit in the neighbouring cell, then they are separated by black dot. The dot between 1 and 2 can be either white or black.

- Digits along each line are monotonically increasing or decreasing.

- Digits along each line are monotonically increasing or decreasing.

- Digits do not repeat along the marked diagonals.

- Digits do not repeat along the marked diagonals.

- Each number outside the grid is the sum of the first X numbers placed in the corresponding direction, where X is equal to the first number placed in that direction.
- There are some dots between cells. The numbers on each side of a dot must always be consecutive. Not all possible dots are marked.

- Each number outside the grid is the sum of the first X numbers placed in the corresponding direction, where X is equal to the first number placed in that direction.

- Each number outside the grid is the sum of the first X numbers placed in the corresponding direction, where X is equal to the first number placed in that direction.

- The digits in two orthogonally adjacent cells cannot have a sum of either 5 or 10.

- The digits in two orthogonally adjacent cells cannot have a sum of either 5 or 10.

- If digit ‘n’ is placed in a cell with an arrow, digit ‘n+1’ must be placed in one of the cells pointed by the arrow.

- If digit ‘n’ is placed in a cell with an arrow, digit ‘n+1’ must be placed in one of the cells pointed by the arrow.

- Cells with circles must contain digits 1-2-3, cells with squares must contain digits 4-5-6, blank cells must contains digits 7-8-9.

- Cells with circles must contain digits 1-2-3, cells with squares must contain digits 4-5-6, blank cells must contains digits 7-8-9.