What Is a Number Puzzle? Definition, Kinds and Worked Examples
A number puzzle is a puzzle whose clues and answer are about numbers. Its parts, main kinds, how it differs from an exercise, and what makes a good one.
Riddle10 blog
Number puzzles
Patterns, sums and sequences.
Number puzzles turn on patterns, sums and sequences. The articles in this section walk through each puzzle with simple arithmetic, show where the usual mistakes come from and explain why the answer is the only one that fits.
Start here: number sequence puzzles, sum grid puzzles, coin total puzzles
Types of Number Puzzles: Six Kinds and How to Crack Each
Sequences, equations, digit riddles, weighing and counting, rod equations and board sums: the six types of number puzzles, with worked examples.
Equal Sum Square Puzzles: How to Fill Every Row and Column
Fill a square so every row and column adds to the same total. The one-gap rule, the centre rule, a worked four by four puzzle and a practice grid.
Coin Total Puzzles: Largest Unpayable Total and Fewest Tokens
Which totals can two token values pay, what is the largest one they cannot, and how few tokens will do? A ladder method, worked example and practice.
Derangement Puzzles: How to Count Mix-Ups With Nothing in Place
How to count and solve derangement puzzles where no jar, key or tile may stay in its own place, with the counting rule, a table and a clue puzzle.
Arithmetic Progression Puzzles: Keep Numbers Unevenly Spaced
Pick as many numbers as you can with no three evenly spaced. The midpoint test, greedy pass and doubling trick, with worked examples and practice.
Number Sequence Puzzles: How to Find What Comes Next
Check the gaps, then the gaps between gaps, then the sum of the two previous terms. Worked number sequence puzzles, no-repeat strings and practice.
How to Solve Sum Grid Puzzles: Runs, Totals and Digit Sets
Learn the totals that allow only one set of digits, use crossing runs and the no-repeat rule, then follow a worked sum grid puzzle and try a practice grid.
Calculation Cage Puzzles: How to Solve Target-and-Operation Grids
Start with single cells and one-pair cages, list digit sets for sums and products, then use rows and columns. A worked grid and a practice puzzle.
Inequality Number Puzzles: How to Solve Greater-Than Grids
Use each sign to strike out digits, follow chains and valleys, and finish with row and column scans. A full worked grid and a practice puzzle.