Cryptographic

Level 1 Level 2 Level 3 Level 4 Level 5 Level 6 Level 7 Level 8 Level 9 Level 10 More Puzzles

In this grid-shading puzzle, each square is either red or white. Some of the red squares may 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 red 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 red squares, each of which will have at least one white square separating them.

Click on a square to make it red. Click the square again if you have made a mistake and it will return to white.

If you are certain a square should remain white you can double-click it.

Graphic

 

 

Wrong

Hide this message

Start Again Check

The solutions to this and other Transum puzzles, exercises and activities are available here when you are signed in to your Transum subscription account. If you do not yet have an account and you are a teacher, tutor or parent you can apply for one by completing the form on the Sign Up page.

A Transum subscription also gives you access to the 'Class Admin' student management system, downloadable worksheets, many more teaching resources and opens up ad-free access to the Transum website for you and your pupils.

The puzzle was created as a child-accessible version of the puzzle included in the 2015 Christmas cards sent by the director of GCHQ, Britain’s security and intelligence organisation. The puzzle was the first section of a challenging quiz.

As can be seen from the following article which appeared in The Times newspaper in January 2016, the later sections of the GCHQ quiz are particularly difficult.

Report in The Times

The following article appeared on February 5th 2016.

Report in The Times

Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for those learning Mathematics anywhere in the world. Click here to enter your comments.

Suggested

Unbeknownst

Unbeknownst

Some picture grid puzzles which can be solved by using simultaneous equations.

The short web address is:

Transum.org/go/?to=unbeknownst

Suggested

Path Puzzle

Path Puzzle

A great puzzle requiring you to use all of the cards to create a continuous red line from start to finish.

The short web address is:

Transum.org/go/?to=pathpuzzle

Suggested

Scheduling Puzzle

Scheduling Puzzle

Make a schedule for the 24-hour Darts Marathon which will take into account everyone's requests and keep everyone happy.

The short web address is:

Transum.org/go/?to=scheduling

Apple

©1997-2021 WWW.TRANSUM.ORG