A Sudoku puzzle will begin with a few digits already in place. The solver’s task, is to figure out which numeral belongs in the remaining empty spaces.

As with most such activities, practice makes perfect with Sudoku. The puzzles that seem impossible at first glance eventual become more manageable.

The name Sudoku is derived from the phrase single number in the Japanese language. Nevertheless, its definition refers to the placement or allotment of a single number

Which of the following alternatives to the underlined portion would be LEAST acceptable?

This puzzle is aptly named, since the misplacement of a single number spells the beginning of an incorrect solution.

For this reason, Sudoku should have been played using a pencil with a good eraser.

It is nearly impossible to discern which number the solver has placed incorrectly once an error is discovered. If you don’t have a pencil, use a pen to write the digit as a series of light dots.

This way, should you make a mistake, you can retrace your steps to locate and correct the original errant placement.

There are certain strategies involved in solving a Sudoku puzzle, including the process of elimination. For example, if a row of nine spaces already has the number 4, that row cannot contain another 4. This goes for columns as well. The solver can use these clues and a bit of deduction to limit the possible combinations of numbers. By attacking the puzzle using logic, you can turn the process into an amusing challenge rather than an impossible task.

The best placement for the underlined portion would be:

[1] The origin of Sudoku is attributed to Leonhard Euler, the Swiss mathematician who sometimes developed the game Magic Squares in 1783. [2] In fact, Euler’s game was actually based on a game derived from Chinese folklore.

If the writer were to divide the preceding paragraph into two shorter paragraphs in order to differentiate between the origin and evolution of the game and the difficulty of playing the game, the new paragraph should begin with Sentence:

[1] The origin of Sudoku is attributed to Leonhard Euler, the Swiss mathematician who sometimes developed the game Magic Squares in 1783. [2] In fact, Euler’s game was actually based on a game derived from Chinese folklore. [3] The primary difference between Magic Squares and Sudoku is that Euler’s game has no grid dividing the puzzle and it is somewhat easier to solve, since there are multiple possibilities for a solution. [4] In true Sudoku, each puzzle has only one solution. [5] The puzzle’s difficulty varies according to the number of digits that are initially provided. [6] When faced with a puzzle with only one 3 provided, for example, you can be sure that it will be more difficult to solve than a puzzle that already has half of the numbers placed in the correct boxes. 59

This question asks about the preceding passage as a whole. If the writer were to delete the final paragraph from the essay, which of the following would be lost?

One has only to examine a local newspaper to ascertain the popularity of this addictive brain teaser. Where comics and crossword puzzles reign supreme, it is often easy to locate a grid of spaces and numbers tucked off in a corner, or even sitting boldly next to the time-honored crossword.