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 2023

Advent calendar 2022

Advent calendar 2021

Advent calendar 2020


List of all puzzles

Tags

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

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2024