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A-Level Problem solving (GCHQ Christmas)

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Last edit: 04 December 2025

AS/A-Level AQA COMP1

Britain's most secretive organisation - GCHQ - has added a cryptic twist to Christmas card season by including a baffling brainteaser. This year spy agency director Robert Hannigan is sending out a complex grid-shading puzzle inside his traditional Christmas cards of the nativity scene. Successful codebreakers will uncover an image in the grid that leads to a series of tougher challenges.

Mr Hannigan is asking players who complete all the stages to submit their answer to GCHQ by the end of January. Those who enjoyed the challenge are asked to make a donation to the National Society for the Prevention of Cruelty to Children.

  • Each square is either black or white. Some of the black squares have already been filled in for you.
  • Each row or column is labelled with a string of numbers. The numbers indicate the length of all consecutive runs of black squares and are displayed in the order that the runs appear in that line. For example, a label "2 1 6" indicates sets of two, one and six black squares, each of which will have at least one white square separating them
  • Complete the grid with a black pen (Taken From BBC)

I've put the puzzle into excel format so that pupils can have a play with it (shade and unshading cells)- We have just finished the problem solving unit of AQA A-Level so this will tie in nicely.

No solution yet as I am going to try it now