Advanced solving for people who already know the rules: named techniques, deduction patterns, and difficulty ladders for sudoku, logic, and number puzzles. Also useful for publishers who need to grade difficulty honestly.
A vocabulary quiz asks one translation question per page — an English word and up to four possible translations, or a foreign word and up to four possible English meanings — with a lettered answer strip to mark. This guide explains the rules, how the three wrong answers are built, and how to work out the answer instead of guessing at it.
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Some Suguru boards go down in one long run of forced cells. You read a cage, you see the one digit that fits, you write it, and the cell next door opens up. Then you meet a board that stops. Twenty cells are filled, sixteen are empty, and every cage you look at has two
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A Shikaku puzzle is a grid with numbers scattered through it, and the whole job is to cut that grid into rectangles. It takes about thirty seconds to learn and rather longer to get good at, and the gap between those two is where some solvers give up. The walkthrough below uses one original 7×7
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After the 9×9 rules, the next two scans that place a digit without guessing are Naked Singles and Hidden Singles. A Naked Single is a cell that has only one legal digit left. A Hidden Single is a digit that has only one legal cell left in a row, column, or 3×3 box. Each section below works one mini-grid.
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After the N×N rules, the fills that place a symbol without guessing are last-symbol in a line, Naked Singles, and Hidden Singles. A Naked Single is a cell whose row and column leave one leftover. A Hidden Single is a symbol that has only one legal cell left in a row or a column. There are no boxes. Each section below works one 5×5.
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After Naked Singles and Hidden Singles, the next scan that makes progress without guessing is a pair. A Naked Pair is two empty cells in the same row, column, or 3×3 box that hold the same two leftover digits. A Hidden Pair is two digits that have only two legal cells left in that house. Neither scan writes a digit. Each one strikes leftovers so a later single can place.
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X-Wing is a later advanced scan, after singles, pairs, triples, quads, pointing pairs, and box-line reduction. An X-Wing is one leftover digit that has only two homes in each of two rows, and those homes sit in the same two columns — a rectangle. The same lock with two columns and two rows is the other orientation. The scan does not write the digit. It strikes that digit from every other empty in the two cover lines.
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How to play Wordoku: it is letter Sudoku with a hidden word. The symbols are the distinct letters of one word. Fill every empty cell so each row, each column, and each box holds those letters exactly once. One row or column starts completely blank — on a board like this one, when you finish it, it spells the word. This guide uses a 6×6 board whose hidden line is STUDIO.
A multiple-choice quiz puzzle puts one question on a page with two to five lettered answers and a strip of answer boxes underneath, and exactly one answer is right. This guide explains how a printed quiz page is laid out, how the answer key works, and how to work out the right answer when you are not certain.
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Fill a 9×9 Sudoku so each row, each column, and each 3×3 box contains the digits 1 through 9 exactly once. Then a Very Easy example shows the first fills: start in a nearly-full 3×3 box, then finish a row the same way. Looking up a variant? Jump to [Dot Sudoku](#dot-sudoku), [Hyper Sudoku](#hyper-sudoku), or [Multidoku](#multidoku).