Digital Circuits
Numeration Systems
19 questions By Tony R. Kuphaldt
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Question 4 of 19
The ancient Mayans used a vigesimal, or base-twenty, numeration system in their mathematics. Each “digit” was a actually a composite of dots and/or lines, as such:

To represent numbers larger than twenty, the Mayans combined multiple “digits” the same way we do to represent numbers larger than ten. For example:

Based on the examples shown above, determine the place-weighting of each “digit” in the vigesimal numeration system. For example, in our denary, or base-ten, system, we have a one’s place, a ten’s place, a hundred’s place, and so on, each successive “place” having ten times the “weight” of the place before it. What are the values of the respective “places” in the Mayan system?
Also, determine the values of these Mayan numbers:

Reveal answerPlace weights: one’s, twenty’s, four hundred’s, eight thousand’s, . . .

Notes:Although no one counts in “Mayan” anymore, this question is still relevant because it gets students thinking outside their accustomed numeration system. Also, it has some cultural value, showing them that not everyone in the world counts the same way they do!
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Question 5 of 19
Digital computers use a numeration system with a base of two, rather than a base of ten as we are accustomed to using. It is much easier to engineer circuitry that counts in “binary” than it is to design circuits that count in any other base system. Based on what you know of numeration systems, answer the following questions:
- How many different symbols (ciphers) are there in the binary numeration system?
- What are the different place-weight values in the binary system?
- How would you represent the number “seventeen” in binary?
- In our base-ten (denary) numeration system, each character is called a “digit.” What is each character called in the binary numeration system?
Reveal answerThere are only two valid ciphers in the binary system: 0 and 1. Each successive place carries twice the “weight” of the one before it. Seventeen = 10001 (in binary). Each character in the binary system is called a “bit” rather than a “digit”.
Notes:Ask your students to hypothesize why binary is used in digital circuitry rather than base-ten (denary) numeration. I’ve revealed that it’s easier to build circuits representing quantities in binary than any other numerical base, but why?
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Question 6 of 19
If a digital meter display has four digits, it can represent any number from 0000 to 9999. This constitutes ten thousand unique numbers representable by the display. How many unique numbers could be represented by five digits? By six digits?
If an ancient Mayan ledger had spaces for writing numbers with three “digits” each, how many unique numbers could be represented in each space? What if the spaces were expanded to hold four “digits” each?
If a digital circuit has four bits, how many unique binary numbers can it represent? If we expanded its capabilities to eight bits, how many unique numbers could be represented by the circuit?
After answering these questions, do you see any mathematical pattern relating the number of “places” in a numeration system and the number of unique quantities that may be represented, given the “base” value (“radix”) of the numeration system? Write a mathematical expression that solves for the number of unique quantities representable, given the “base” of the system and the number of “places”.
Reveal answerFive denary digits: one hundred thousand unique numbers. Six denary digits: one million unique numbers.
Three vigesimal “digits”: eight thousand unique numbers. Four vigesimal “digits”: one hundred sixty thousand unique numbers.
Four binary bits: sixteen unique numbers. Eight binary bits: two hundred fifty six unique numbers.
Unique numbers = bn Where,
b = Radix of numeration system.
n = Number of “places” given.
Notes:Ask your students which numeration system of the three given is more efficient in representing quantities with the smallest number of places. Then, ask them to explain why this is.



