# 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

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

In a week (Monday 12:01 to Monday 12:01 a week later), how many times will the minute hand of an analogue clock point in the same direction as the hour hand?

## Ticking clock

Is there a time of day when the hands of an analogue clock (one with a second hand that moves every second instead of moving continuously) will all be 120° apart?

## 8! minutes

How many weeks are there in 8! (\(8\times 7\times 6\times 5\times 4\times 3\times 2\times 1\)) minutes?

## Burning ropes

Source: Richard Wiseman's Blog

You have two ropes and some matches. Each rope, if lit at its end, will burn for 60 minutes. But the rate of burning is not regular, so cutting a rope in half doesn't result in a burn time of 30 minutes.

How can you use the ropes to time exactly 45 minutes?