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

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

Archive

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