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A card with holes can hold a number. It can hold a letter too.

This is Punched Cards & a Lights Puzzle. It uses what you know about bits, patterns and codes. Your school handbook has a punched-card activity and a lights puzzle. This track covers both.

What you will learn

• Numbers on cards. Each place is twice the place on its right.
• Letters on cards. Five holes are enough for 26 letters.
• Sorting with a needle. One hole at a time sorts the deck.
• A lights puzzle. Each clue keeps only some of the 32 settings.

Need a quick recap?

• A bit — one switch with two states.
• A pattern — one full setting of all the switches.
• A code — an agreed table of pattern and meaning.