This illustration shows the board after you have invoked the F3 function, either by hitting the function key or clicking on the F3 icon on the Sudoku board. Note that for each row, column and box, the numbers that remain to be placed are listed...IF...and this differs from the F4 function which shows all case...if there are fewer than five remaining to be placed.
This is how the Sudoku board will look after the F4 function is invoked. The display is similar to that of the F3 function, but in this case ALL remaining numbers to be placed are listed.
Only one of these two functions can be in play at one time. If one is chosen while the other is in play, it will replace it and the display will change accordingly.
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This illustration shows the board after you have invoked the F3 function, either by hitting the function key or clicking on the F3 icon on the Sudoku board. Note that for each row, column and box, the numbers that remain to be placed are listed...IF...and this differs from the 
This is how the Sudoku board will look after the F4 function is invoked. The display is similar to that of the