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Secondary 2 · Mathematics
Numbers · Other number systems

Other Numeral Systems

Before you start, make sure you know: Properties of Exponents (Secondary Year 1 (first cycle))

A computer only understands $0$ and $1$. A Mayan inscription uses dots and bars. On the front of an old theater in Santiago you can see "MCMXCVIII". Our decimal system (base $10$) is not the only possible one: any number can be written in any base, by changing how many symbols you use and how much each position is worth. By the end of this page you will know how to read all three.

The Decimal System Is Not the Only One: What a Base Is

In base $10$ we use $10$ symbols ($0$ through $9$) and each position is worth $10$ times the previous one. In base $2$ (binary) there are only two symbols, $0$ and $1$, and each position is worth double the previous one.

Comparison of place value between base 10 and base 2, with the expansion of the binary number 1101 to decimal. Base 10: ... 1000 100 10 1 Base 2: ... 2³=8 2²=4 2¹=2 2⁰=1 1101₂ = 1·8 + 1·4 + 0·2 + 1·1 = 13
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In computer science, the smallest unit of information is the bit, which can only take the values $0$ or $1$ (binary system). An old processor in a retro console uses…

In computer science, the smallest unit of information is the bit, which can only take the values $0$ or $1$ (binary system). An old processor in a retro console uses 8-bit registers. If a character has an energy level represented by the decimal number $43$, how would that value appear in the console's binary code?

Energy: 43₁₀ ? ? ? ? ? ? ? ? 2⁷ 2⁶ 2⁵ 2⁴ 2³ 2² 2¹ 2⁰ 128 64 32 16 8 4 2 1 8-bit register (Binary System)
Solve

From Decimal to Binary: Successive Divisions

To go the other way, you divide the number by $2$ over and over; the remainders, read from last to first, form the binary number.

Successive divisions by 2 to convert the decimal number 13 to binary, reading the remainders in reverse order. 13 : 2 = 6 remainder 1 6 : 2 = 3 remainder 0 3 : 2 = 1 remainder 1 1 : 2 = 0 remainder 1 remainders from bottom to top: 1101
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Computers use the binary system (base 2) to process information, using only the digits $0$ and $1$. To understand how a machine "thinks", convert the decimal number $13$…

Computers use the binary system (base 2) to process information, using only the digits $0$ and $1$. To understand how a machine "thinks", convert the decimal number $13$ to binary code using the method of successive divisions by $2$.

The diagram shows the divisions you need to do. In each row, the quotient from the previous row is divided by $2$, and you continue until the quotient is $0$.

Diagram of four successive divisions by 2 starting at 13, with empty boxes for the quotients and remaindersDividendQuotientRemainder13???????????÷ 2 =÷ 2 =÷ 2 =÷ 2 =remainderremainderremainderremainder
  1. a) Fill in the boxes of the diagram: the quotient and remainder of each division, until you reach a quotient of $0$.
  1. b) Read the remainders from bottom to top (from the last to the first) and write the number $13$ in base 2.
Solve
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In a computer system, multiplying a binary number by $2^n$ is equivalent to shifting its digits $n$ positions to the left (adding zeroes at the end). Given the decimal…

In a computer system, multiplying a binary number by $2^n$ is equivalent to shifting its digits $n$ positions to the left (adding zeroes at the end).

Given the decimal number $21$:

  1. a) Express it in the binary system.
  2. b) Perform the operation of shifting its digits $3$ positions to the left.
  3. c) Convert the resulting number back to the decimal system and check that the result is equivalent to multiplying $21 \times 2^3$.
Solve

Bits, Bytes and Powers of 2

The memory of a cell phone or a computer is measured in units that are powers of $2$. A bit is a single $0$ or $1$. A byte is $8$ bits, or $2^3$ bits. After that, each unit is worth $1024 = 2^{10}$ times the previous one.

Unit Equals In powers of 2
1 byte 8 bits $2^3$ bits
1 KB 1024 bytes $2^{10}$ bytes
1 MB 1024 KB $2^{20}$ bytes
1 GB 1024 MB $2^{30}$ bytes
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A file server for an esports gaming community has a total capacity of $2^{35}$ bits. Currently, the server contains three folders with game screenshots: folder A…

A file server for an esports gaming community has a total capacity of $2^{35}$ bits. Currently, the server contains three folders with game screenshots: folder A occupies $1.2$ GB, folder B occupies $950$ MB and folder C contains $2^{30}$ bytes. Given that $1$ GB = $1024$ MB and $1$ MB = $1024$ KB, determine whether it is possible to save an additional video of $1.5$ GB without exceeding the server's total capacity. Express all calculations as powers of base 2 where possible.

Solve

Roman Numerals

Roman numerals are not positional: each symbol has a fixed value and they are combined by adding or subtracting depending on the order.

Table with the symbols of Roman numerals and examples of numbers formed by subtraction such as XC and CM. I=1 · V=5 · X=10 · L=50 C=100 · D=500 · M=1000 XC = 100 − 10 = 90 CM = 1000 − 100 = 900

Writing a Number in Roman Numerals

To go the other way, you break the number down into thousands, hundreds, tens and ones, and write each part separately.

1 2 3 4 5 6 7 8 9
Ones I II III IV V VI VII VIII IX
Tens X XX XXX XL L LX LXX LXXX XC
Hundreds C CC CCC CD D DC DCC DCCC CM

Thousands are written with M: $1000=M$, $2000=MM$, $3000=MMM$. For numbers greater than $3999$ you keep writing M's in a row (for example, $6000 = MMMMMM$).

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On the façade of an old theater in your city, the year of its opening is carved in Roman numerals: MCMXCVIII. Convert this number to our decimal system to find out which…

On the façade of an old theater in your city, the year of its opening is carved in Roman numerals: MCMXCVIII. Convert this number to our decimal system to find out which year the theater opened.

M CM XC VIII I = 1 V = 5 X = 10 C = 100 M = 1000
Solve
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Calculate the result of the following operation with Roman numerals, expressing the final value both in Roman numerals and in the decimal number system:…

Calculate the result of the following operation with Roman numerals, expressing the final value both in Roman numerals and in the decimal number system:

$(MMCDLXIV - MDCCCLXXXIX) \times XII$

Solve

Other Systems: Mayan and Other Bases

Not all civilizations used base $10$. The Mayans used base $20$ (vigesimal), with dots and bars stacked in levels. Other peoples used base $60$, the one we still use today for hours and minutes.

Mayan numeral system in three vertical levels according to powers of 20: one dot on top, two bars and three dots in the middle, and one bar at the bottom. level 3: × 20² level 2: × 20¹ level 1: × 20⁰ dot = 1, bar = 5 (Mayan, base 20)
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The Mayan number system was vigesimal (base 20) and vertically positional. Look at the following number represented by its levels and convert it into our decimal system:…

The Mayan number system was vigesimal (base 20) and vertically positional. Look at the following number represented by its levels and convert it into our decimal system:

  • Level 3 (top): One dot.

  • Level 2 (middle): Two bars and three dots.

  • Level 1 (bottom): One bar.

(Remember that in the Mayan system, the dot is worth $1$ and the bar is worth $5$).

Level 3 × 20² (400) Level 2 × 20¹ (20) Level 1 × 20⁰ (1)
Solve
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In an archaeological dig, an inscription with an unknown number system was found. After analyzing it, experts determined that it is a base-4 system, where the symbols…

In an archaeological dig, an inscription with an unknown number system was found. After analyzing it, experts determined that it is a base-4 system, where the symbols are: $\triangle = 0$, $\square = 1$, $\bigcirc = 2$ and $\star = 3$.

If the treasure is located at a distance of $\bigcirc \star \square \triangle$ meters from the main entrance, calculate this distance in our decimal system. Then, express the result obtained in the binary system.

SYMBOLS (BASE 4)
Solve
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An intergalactic explorer has arrived on a planet where the natives use a base 5 numeral system. You are given the following equivalences to understand their language:…

An intergalactic explorer has arrived on a planet where the natives use a base 5 numeral system. You are given the following equivalences to understand their language:

$1_{5} = \text{I}$, $2_{5} = \text{V}$, $3_{5} = \text{X}$, $4_{5} = \text{L}$.

If they tell you that there are $\text{XXL}$ hours left until the mothership takes off:

  1. a) Write the number of hours in the decimal system.
  2. b) Calculate how many minutes that time is equivalent to.
Solve

Summary

See all the exercises in this section