mscroggs.co.uk
mscroggs.co.uk

subscribe

Advent calendar 2015

23 December

This number is a prime number. If you treble it and add 16, the result is also prime. Repeating this will give 11 prime numbers in total (including the number itself).

Archive

Show me a random puzzle
 Most recent collections 

Advent calendar 2025

Advent calendar 2024

Advent calendar 2023

Advent calendar 2022


List of all puzzles

Tags

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

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2026