Codes and signals quiz
Checked on 4 November 2026
Question 1 of 10
Discover
How many raised dots make up a full braille cell?
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The answer is Six.
A full braille cell has six raised dots, set out in two columns of three.
Discover
What do the letters QR stand for in QR code?
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The answer is Quick Response.
QR is short for quick response, as the code was designed to be read quickly by a scanner.
Discover
In modern flag semaphore, how many flags does the signaller hold?
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The answer is Two.
The signaller holds one square flag in each hand and points the arms in different directions to show each letter.
Discover
What does ISBN, the number printed on books, stand for?
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The answer is International Standard Book Number.
ISBN stands for International Standard Book Number, a unique code given to each edition of a book.
Practise
Braille grew out of an earlier tactile code developed by Charles Barbier. What is that code known as?
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The answer is Night writing.
Louis Braille based his system on Charles Barbier's tactile code, now known as night writing.
Practise
In June 1974, what was the first product scanned at a shop checkout using a UPC barcode?
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The answer is A pack of chewing gum.
A 10-pack of Wrigley's Juicy Fruit gum was the first item scanned in the first commercial use of the UPC barcode.
Practise
When flag semaphore is used at sea, what colours are the flags?
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The answer is Red and yellow.
Semaphore flags used at sea are red and yellow, while flags used on land are usually white and blue.
Expert
Morse code is named after Samuel Morse, but who developed the alphabet-based code that replaced his first proposal?
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The answer is Alfred Vail.
Samuel Morse was one of several developers, and his early proposal was replaced by an alphabet-based code developed by Alfred Vail.
Expert
In Morse code, how many times longer than a dit (dot) is a dah (dash)?
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The answer is Three.
In Morse code timing, a dah lasts three times as long as a dit.
Expert
In a 10-digit ISBN, which number does a final check digit of X represent?
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The answer is 10.
The ISBN-10 check digit can range from 0 to 10, and the symbol X is used when it equals 10.