Christmas card 2018

Just like last year and the year before, TD and I spent some time in November this year designing a Chalkdust puzzle Christmas card.
The card looks boring at first glance, but contains 10 puzzles. By splitting the answers into pairs of digits, then drawing lines between the dots on the cover for each pair of digits (eg if an answer is 201304, draw a line from dot 20 to dot 13 and another line from dot 13 to dot 4), you will reveal a Christmas themed picture. Colouring the region of the card labelled R red or orange will make this picture even nicer.
If you want to try the card yourself, you can download this pdf. Alternatively, you can find the puzzles below and type the answers in the boxes. The answers will be automatically be split into pairs of digits, lines will be drawn between the pairs, and the red region will be coloured...
If you enjoy these puzzles, then you'll almost certainly enjoy this year's puzzle Advent calendar.

Similar posts

Christmas card 2019
Christmas card 2017
Christmas card 2016
Christmas (2019) is over


Comments in green were written by me. Comments in blue were not written by me.
Someone told me I would like this puzzle and they were right!
×1                 Reply
@Carmel: It's not meant to check your answers. It only shows up red if the number you enter cannot be split into valid pairs (eg the number has an odd number of digits or one of the pairs of digits is greater than 20).
The script for checking the answers doesn't work properly
Thank you Shawn!
So satisfying!
×1                 Reply
Great puzzle problems! Hint on #9: try starting with an analogous problem using smaller numbers (e.g. 3a + 10b). This helped me to see what I had to do more generally.
   ×1              Reply
 Add a Comment 

I will only use your email address to reply to your comment (if a reply is needed).

Allowed HTML tags: <br> <a> <small> <b> <i> <s> <sup> <sub> <u> <spoiler> <ul> <ol> <li>
To prove you are not a spam bot, please type "prime" in the box below (case sensitive):


Show me a random blog post

May 2020

A surprising fact about quadrilaterals
Interesting tautologies

Mar 2020

Log-scaled axes

Feb 2020

PhD thesis, chapter ∞
PhD thesis, chapter 5
PhD thesis, chapter 4
PhD thesis, chapter 3
Inverting a matrix
PhD thesis, chapter 2

Jan 2020

PhD thesis, chapter 1
Gaussian elimination
Matrix multiplication
Christmas (2019) is over
▼ show ▼
▼ show ▼
▼ show ▼
▼ show ▼
▼ show ▼
▼ show ▼
▼ show ▼
▼ show ▼


graphs captain scarlet python determinants news rugby gaussian elimination polynomials tmip a gamut of games reuleaux polygons rhombicuboctahedron braiding pizza cutting matrix of cofactors puzzles arithmetic javascript matrix of minors bubble bobble simultaneous equations games cambridge reddit game of life hannah fry triangles chalkdust magazine world cup fractals football london christmas big internet math-off harriss spiral curvature inverse matrices realhats wave scattering asteroids final fantasy logs talking maths in public sport national lottery programming sound mathslogicbot christmas card go probability chess matrix multiplication dataset map projections hexapawn raspberry pi exponential growth weather station pac-man london underground nine men's morris data stickers matrices tennis preconditioning wool binary numerical analysis royal institution countdown plastic ratio golden spiral error bars manchester science festival radio 4 menace matt parker computational complexity signorini conditions golden ratio advent calendar boundary element methods sorting the aperiodical finite element method graph theory noughts and crosses quadrilaterals logic geogebra phd latex books light misleading statistics game show probability speed ucl oeis dates trigonometry craft flexagons machine learning mathsteroids european cup frobel estimation ternary bodmas mathsjam manchester folding tube maps cross stitch video games chebyshev php hats interpolation bempp dragon curves squares inline code platonic solids folding paper palindromes approximation electromagnetic field sobolev spaces royal baby geometry convergence martin gardner gerry anderson propositional calculus people maths weak imposition statistics twitter data visualisation draughts accuracy pythagoras coins


Show me a random blog post
▼ show ▼
© Matthew Scroggs 2012–2020