Last week, during the school holiday, my wife took our daughters to a National Trust property. My oldest has to prepare a piece on Victorian England, so where better to go than a historic home and mill?

During the tour around the mill both girls made key rings, beads strung in the form of a binary number representation of the initials of their first and last names.

The next day I got together with my youngest to decode the beads, adopting a methodical approach:

• Explain what binary numbers are used for these days,
• Explain what they were used for in the olden-days,
• Sketch out a table of 7-bit binary, and extend it to 8 bits,
• Note down the first set of beads, being careful to establish a datum from which to start, in case we chose the wrong end first,
• Add up the filled 1, 2, 4, 8, 16, 32, 64 and 128 positions, explaining why,
• Find an ASCII character table from the Internet to decide which character the number represents,
• Repeat for the second letter, which proved we'd chosen the wrong end from which to start, but it didn't matter for the first,
• Success!

Ok, you get the idea. A surprisingly fun thing to do on a miserably mild English winter afternoon.