Advent calendar 2020

6 December

There are 12 ways of placing 2 tokens on a 2×4 grid so that no two tokens are next to each other horizonally, vertically or diagonally:
Today's number is the number of ways of placing 5 tokens on a 2×10 grid so that no two tokens are next to each other horizonally, vertically or diagonally.

Show answer


Show me a random puzzle
 Most recent collections 

Advent calendar 2020

Advent calendar 2019

Sunday Afternoon Maths LXVII

Coloured weights
Not Roman numerals

Advent calendar 2018

List of all puzzles


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


Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2021