# Puzzles

## Archive

Show me a random puzzle**Most recent collections**

#### Sunday Afternoon Maths LXVII

Coloured weightsNot Roman numerals

#### Advent calendar 2018

#### Sunday Afternoon Maths LXVI

Cryptic crossnumber #2#### Sunday Afternoon Maths LXV

Cryptic crossnumber #1Breaking Chocolate

Square and cube endings

List of all puzzles

## Tags

triangles folding tube maps squares number crossnumbers triangle numbers advent symmetry coins partitions integers wordplay factors doubling ellipses integration volume polygons christmas unit fractions cards odd numbers books division games sum to infinity balancing routes taxicab geometry prime numbers perimeter floors indices ave arrows time hexagons grids mean sums dodecagons chalkdust crossnumber chess sequences means spheres square numbers proportion money coordinates clocks averages differentiation square roots quadratics fractions remainders numbers calculus crosswords factorials cube numbers speed graphs trigonometry rugby rectangles planes colouring circles palindromes scales geometry functions shapes percentages regular shapes area sport surds chocolate probability 3d shapes 2d shapes star numbers pascal's triangle menace shape perfect numbers parabolas people maths digits addition multiplication multiples probabilty lines irreducible numbers algebra cryptic clues logic complex numbers dates bases cryptic crossnumbers angles dice## Lights

Source: Maths Jam

You have been taken captive and are blindfolded. There is a table in front of you with four lights on it. Some are on, some are off: you don't know how many and which ones. You need to get either all the lights on or all the lights off to be released. To do this, you can ask your captor to toggle the light switches of some of the lights. You captor will then rotate the table (so you don't know where the lights you toggled now are). Find a sequence of moves which will always lead to your release.