mscroggs.co.uk
mscroggs.co.uk

subscribe

Puzzles

Dartboard

Concentric circles with radii 1, \(\frac{1}{2}\), \(\frac{1}{3}\), \(\frac{1}{4}\), ... are drawn. Alternate donut-shaped regions are shaded.
What is the total shaded area?

Show answer & extension

If you enjoyed this puzzle, check out Sunday Afternoon Maths XIX,
puzzles about 2d shapes, or a random puzzle.

Archive

Show me a random puzzle
 Most recent collections 

Advent calendar 2024

Advent calendar 2023

Advent calendar 2022

Advent calendar 2021


List of all puzzles

Tags

digital clocks square grids the only crossnumber logic balancing dates decahedra wordplay averages matrices money geometry algebra trigonometry sport sums albgebra surds symmetry mean perfect numbers volume digits bases partitions percentages floors complex numbers integers menace rugby proportion means addition angles unit fractions polynomials integration factorials advent quadratics grids determinants coordinates tiling taxicab geometry consecutive numbers tournaments chocolate elections probabilty dominos multiples colouring range products lines number sum to infinity ellipses division people maths crosswords 3d shapes shape time cards geometric mean dice cryptic clues square roots hexagons chalkdust crossnumber games prime numbers remainders planes powers clocks irreducible numbers arrows expansions chess quadrilaterals circles spheres star numbers square numbers geometric means cryptic crossnumbers coins even numbers neighbours gerrymandering area doubling numbers grids rectangles christmas regular shapes cube numbers medians perimeter differentiation sequences polygons ave triangles cubics triangle numbers pentagons scales functions combinatorics 2d shapes numbers consecutive integers books pascal's triangle factors binary tangents fractions folding tube maps calculus speed routes palindromes graphs multiplication sets dodecagons parabolas crossnumbers squares median shapes probability indices digital products odd numbers axes

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2025