# Blog

## Secret pairs

By Ariel Marcy, 12 March 2024

Lavonne is testing a secret code with her friend Jack. First, she picks 3 different secret numbers between 1 and 9. Then she finds the sum of each pair of numbers. Lavonne wants to know if Jack can figure out the original secret numbers just from the sums?

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## This code’s for oldies

By David Shaw, 12 December 2018

If you’re sitting there twiddling your thumbs, see if you can decode this message. If you need a hint, you can always phone a friend! 3666882255533 443355544499 339987772

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## Coded message brainteaser

By David Shaw, 21 March 2018

You’ve just received a secret coded message: AD, BA, BH, CE, DB, DI, EF You know it follows a pattern, but can you work out what pair of letters come next?

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## Caesar cipher

By David Shaw, 3 March 2015

Learn the Caesar cipher, one of the oldest codes ever devised!

## Decoding binary numbers

By David Shaw, 13 January 2014

Written by Gabrielle Tramby In this activity you’ll do maths like a computer. It’s a bit tricky, so younger readers may want to read the ‘What’s Happening?’ section first.

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