Decimal Number System – With Types & Properties

A number is a mathematical value used for counting and measuring objects, and for performing arithmetic calculations. 

A number system or numeral system or system of numeration is a way of writing these numbers.  In other words, a number system is a mathematical notation for representing numbers of a given set, using digits or other symbols in a consistent manner.

Decimal Number System

There are many types of number systems in use today depending on their ease and compatibility with the applications they are used for. The most widely used is the Decimal Number System which uses $10$ symbols commonly referred to as digits to form the numbers.

Numbers in the decimal number system have various categories like natural numbers, whole numbers, integers, rational and irrational numbers, and real numbers.

The following figure shows the hierarchy of numbers in different categories of the decimal number system.

number system
Categories of numbers in a decimal number system

What is a Natural Number?

The natural numbers also known as counting numbers are a set of numbers starting from $1$ and moving on to $2$, $3$, $4$, and so on. These are called counting numbers because numbers are significantly used in our day-to-day activities and speech. We see these numbers everywhere around us, for counting objects, representing or exchanging money, measuring the temperature, telling the time, etc.

Natural numbers are represented by the letter ‘$N$’. $N = \{1, 2, 3, 4, ….\}$. There are infinite numbers in the set $N$, i.e., one cannot count all the natural numbers.

Since the natural numbers start from $1$, it is the smallest natural number and there is no largest natural number. You can find a natural number still larger than any large number by just adding $1$ to it.

The set of natural numbers can be shown on the number line below.

Number System

Properties of Natural Numbers

The main properties are shown by natural numbers related to the four basic arithmetic operations, addition, subtraction, multiplication, and division. These properties are

  • Closure Property of Addition & Multiplication
  • Associative Property of Addition & Multiplication
  • Commutative Property of Addition & Multiplication
  • Distributive Property of Multiplication over Addition & Subtraction
  • Existence of Multiplicative Identity Property
Maths in Real Life

What is a Whole Number?

When a number $0$ is included in the set of natural numbers, it is called a set of whole numbers. As seen above the natural numbers are used as counting numbers. But many times you need to represent a number for ‘nothing’, that’s the reason symbol $0$ was introduced, and a set of natural numbers was extended to form a set of whole numbers.

Whole numbers are represented by the letter ‘$W$’. $W = \{0, 1, 2, 3, 4, ….\}$. There are infinite numbers in the set $W$, i.e., one cannot count all the whole numbers.

Since the whole numbers start from $0$, it is the smallest whole number and there is exist no largest whole number. You can find a whole number still larger than any large number by just adding $1$ to it.

The set of whole numbers can be shown on the number line below.

Number System

Properties of Whole Numbers

The main properties are shown by whole numbers related to the four basic arithmetic operations, addition, subtraction, multiplication, and division. These properties are

  • Closure Property of Addition & Multiplication
  • Associative Property of Addition & Multiplication
  • Commutative Property of Addition & Multiplication
  • Distributive Property of Multiplication over Addition & Subtraction
  • Existence of Additive Identity Property
  • Existence of Multiplicative Identity Property
Is your child struggling with Maths?
frustrated-kid
We can help!
Country
  • Afghanistan 93
  • Albania 355
  • Algeria 213
  • American Samoa 1-684
  • Andorra 376
  • Angola 244
  • Anguilla 1-264
  • Antarctica 672
  • Antigua & Barbuda 1-268
  • Argentina 54
  • Armenia 374
  • Aruba 297
  • Australia 61
  • Austria 43
  • Azerbaijan 994
  • Bahamas 1-242
  • Bahrain 973
  • Bangladesh 880
  • Barbados 1-246
  • Belarus 375
  • Belgium 32
  • Belize 501
  • Benin 229
  • Bermuda 1-441
  • Bhutan 975
  • Bolivia 591
  • Bosnia 387
  • Botswana 267
  • Bouvet Island 47
  • Brazil 55
  • British Indian Ocean Territory 246
  • British Virgin Islands 1-284
  • Brunei 673
  • Bulgaria 359
  • Burkina Faso 226
  • Burundi 257
  • Cambodia 855
  • Cameroon 237
  • Canada 1
  • Cape Verde 238
  • Caribbean Netherlands 599
  • Cayman Islands 1-345
  • Central African Republic 236
  • Chad 235
  • Chile 56
  • China 86
  • Christmas Island 61
  • Cocos (Keeling) Islands 61
  • Colombia 57
  • Comoros 269
  • Congo - Brazzaville 242
  • Congo - Kinshasa 243
  • Cook Islands 682
  • Costa Rica 506
  • Croatia 385
  • Cuba 53
  • Cyprus 357
  • Czech Republic 420
  • Denmark 45
  • Djibouti 253
  • Dominica 1-767
  • Ecuador 593
  • Egypt 20
  • El Salvador 503
  • Equatorial Guinea 240
  • Eritrea 291
  • Estonia 372
  • Ethiopia 251
  • Falkland Islands 500
  • Faroe Islands 298
  • Fiji 679
  • Finland 358
  • France 33
  • French Guiana 594
  • French Polynesia 689
  • French Southern Territories 262
  • Gabon 241
  • Gambia 220
  • Georgia 995
  • Germany 49
  • Ghana 233
  • Gibraltar 350
  • Greece 30
  • Greenland 299
  • Grenada 1-473
  • Guadeloupe 590
  • Guam 1-671
  • Guatemala 502
  • Guernsey 44
  • Guinea 224
  • Guinea-Bissau 245
  • Guyana 592
  • Haiti 509
  • Heard & McDonald Islands 672
  • Honduras 504
  • Hong Kong 852
  • Hungary 36
  • Iceland 354
  • India 91
  • Indonesia 62
  • Iran 98
  • Iraq 964
  • Ireland 353
  • Isle of Man 44
  • Israel 972
  • Italy 39
  • Jamaica 1-876
  • Japan 81
  • Jersey 44
  • Jordan 962
  • Kazakhstan 7
  • Kenya 254
  • Kiribati 686
  • Kuwait 965
  • Kyrgyzstan 996
  • Laos 856
  • Latvia 371
  • Lebanon 961
  • Lesotho 266
  • Liberia 231
  • Libya 218
  • Liechtenstein 423
  • Lithuania 370
  • Luxembourg 352
  • Macau 853
  • Macedonia 389
  • Madagascar 261
  • Malawi 265
  • Malaysia 60
  • Maldives 960
  • Mali 223
  • Malta 356
  • Marshall Islands 692
  • Martinique 596
  • Mauritania 222
  • Mauritius 230
  • Mayotte 262
  • Mexico 52
  • Micronesia 691
  • Moldova 373
  • Monaco 377
  • Mongolia 976
  • Montenegro 382
  • Montserrat 1-664
  • Morocco 212
  • Mozambique 258
  • Myanmar 95
  • Namibia 264
  • Nauru 674
  • Nepal 977
  • Netherlands 31
  • New Caledonia 687
  • New Zealand 64
  • Nicaragua 505
  • Niger 227
  • Nigeria 234
  • Niue 683
  • Norfolk Island 672
  • North Korea 850
  • Northern Mariana Islands 1-670
  • Norway 47
  • Oman 968
  • Pakistan 92
  • Palau 680
  • Palestine 970
  • Panama 507
  • Papua New Guinea 675
  • Paraguay 595
  • Peru 51
  • Philippines 63
  • Pitcairn Islands 870
  • Poland 48
  • Portugal 351
  • Puerto Rico 1
  • Qatar 974
  • Romania 40
  • Russia 7
  • Rwanda 250
  • Réunion 262
  • Samoa 685
  • San Marino 378
  • Saudi Arabia 966
  • Senegal 221
  • Serbia 381 p
  • Seychelles 248
  • Sierra Leone 232
  • Singapore 65
  • Slovakia 421
  • Slovenia 386
  • Solomon Islands 677
  • Somalia 252
  • South Africa 27
  • South Georgia & South Sandwich Islands 500
  • South Korea 82
  • South Sudan 211
  • Spain 34
  • Sri Lanka 94
  • Sudan 249
  • Suriname 597
  • Svalbard & Jan Mayen 47
  • Swaziland 268
  • Sweden 46
  • Switzerland 41
  • Syria 963
  • Sao Tome and Principe 239
  • Taiwan 886
  • Tajikistan 992
  • Tanzania 255
  • Thailand 66
  • Timor-Leste 670
  • Togo 228
  • Tokelau 690
  • Tonga 676
  • Trinidad & Tobago 1-868
  • Tunisia 216
  • Turkey 90
  • Turkmenistan 993
  • Turks & Caicos Islands 1-649
  • Tuvalu 688
  • U.S. Outlying Islands
  • U.S. Virgin Islands 1-340
  • UK 44
  • US 1
  • Uganda 256
  • Ukraine 380
  • United Arab Emirates 971
  • Uruguay 598
  • Uzbekistan 998
  • Vanuatu 678
  • Vatican City 39-06
  • Venezuela 58
  • Vietnam 84
  • Wallis & Futuna 681
  • Western Sahara 212
  • Yemen 967
  • Zambia 260
  • Zimbabwe 263
Age Of Your Child
  • Less Than 6 Years
  • 6 To 10 Years
  • 11 To 16 Years
  • Greater Than 16 Years

What is an Integer?

An integer is a signed number. By signed number, we mean a number associated with either a positive ‘$+$’ or a negative ‘$-$’ sign. 

A positive or negative sign before a number makes a huge difference. While positive implies add-on, negative implies decrease. With this idea, the concept of integers originated.

For example, if a profit of ₹$100$ is represented as $+100$ then a loss of ₹$100$ will be represented as $-100$. There are many other real-world applications where signed numbers or integers are used such as representing temperatures, an increase or a decrease in quantity, moving up or down, etc.

A set of integers is a set that includes negative and positive numbers, including zero. A set of integers, which is represented as $Z$, includes:

Positive Numbers: $1$, $2$, $3$, …

Negative Numbers: $-1$, $-2$, $-3$, …

Zero: defined as neither a negative number nor a positive number. It is a whole number.

$Z = \{… -4, -3, -2, -1, 0, 1, 2, 3, 4…\}$

The set of integers can be shown on the number line below.

Number System

Properties of Integers

The main properties are shown by integers related to the four basic arithmetic operations, addition, subtraction, multiplication, and division. These properties are

  • Closure Property of Addition, Subtraction & Multiplication
  • Associative Property of Addition & Multiplication
  • Commutative Property of Addition & Multiplication
  • Distributive Property of Multiplication over Addition & Subtraction
  • Existence of Additive Identity Property
  • Existence of Additive Inverse Property
  • Existence of Multiplicative Identity Property

What is a Rational Number?

The word ‘rational’ originated from the word ‘ratio’. So, rational numbers are the numbers related to the concept of fractions which represent ratios. If a number is expressed as a fraction where both the numerator and the denominator are integers, the number is called a rational number.

Mathematically, a rational number is represented as $\frac {p}{q}$, where both $p$ and $q$ belong to the set $Z$ (set of integers) and $q \ne 0$. The set of rational numbers is denoted by $Q$.

Note: If the denominator of a fraction is $0$, it becomes undefined, because dividing a number by $0$ is meaningless.

Rational numbers can also be expressed as numbers with a decimal point. There are two types of the decimal representation of rational numbers.

  • Terminating Decimal Numbers: are the numbers that do not terminate i.e., with uncountable decimal places, e.g., $2.5$, $-7.8$
  • Non-Terminating but Recurring Decimal Numbers: are the numbers that do not terminate but the decimal digits keep recurring (repeating), e.g., $3.222…$, $-5.434343…$

Note: Non-terminating and non-recurring decimal numbers are called irrational numbers.

Axioms, Postulate & Theorem

Properties of Rational Numbers

The main properties are shown by rational numbers related to the four basic arithmetic operations, addition, subtraction, multiplication, and division. These properties are

  • Closure Property of Addition, Subtraction, Multiplication & Division
  • Associative Property of Addition & Multiplication
  • Commutative Property of Addition & Multiplication
  • Distributive Property of Multiplication over Addition & Subtraction
  • Existence of Additive Identity Property
  • Existence of Additive Inverse Property
  • Existence of Multiplicative Identity Property
  • Existence of Multiplicative Inverse Property

What is an Irrational Number?

Irrational numbers are those real numbers that cannot be represented in the form of a ratio. In other words, those real numbers that are not rational numbers are known as irrational numbers. The set of irrational numbers is denoted by the letter $P$. It’s also denoted by $Q’$ or $\overline{Q}$, meaning ‘not $Q$’, i.e., not a rational number. 

Irrational numbers are the set of numbers that cannot be expressed in the form of a fraction, $\frac {p}{q}$ where $p$ and $q$ and $q \ne 0$. Also, the decimal expansion of an irrational number is neither terminating nor repeating.

Two of the most common examples of an irrational number are $\pi = 3⋅14159265…$ and Euler’s constant $e = 2.7182818…..$. The other examples are $\sqrt{2}$, $\sqrt[3]{2}$, $\sqrt[3]{3}$, $\sqrt[4]{5}$, $\sqrt[7]{11}$.

Properties of Irrational Numbers

Given below are some of the properties of irrational numbers:

  • Closure Property of Addition and Subtraction
  • Associative Property of Addition & Multiplication
  • Commutative Property of Addition & Multiplication
  • Distributive Property of Multiplication over Addition & Subtraction
  • Existence of Additive Inverse Property
  • Existence of Multiplicative Inverse Property
  • Irrational numbers consist of non-terminating and non-recurring decimals

What are Real Numbers?

Any number that can be found in the real world is a real number. The set of real numbers consists of all the natural numbers, whole numbers,  integers, rational numbers, and irrational numbers. In fact, the set of real numbers denoted by $R$ is a superset of all the other sets of numbers, i.e., $R$ = $N + W + Z + Q + P$.

Properties of Real Numbers

Given below are some of the properties of irrational numbers:

  • Closure Property of Addition, Subtraction, Multiplication & Division
  • Associative Property of Addition & Multiplication
  • Commutative Property of Addition & Multiplication
  • Distributive Property of Multiplication over Addition & Subtraction
  • Existence of Additive Inverse Property
  • Existence of Additive Identity Property
  • Existence of Multiplicative Inverse Property
  • Existence of Multiplicative Identity Property

Conclusion

We use numbers in our daily lives. Depending on the application and situation, the numbers used are of different types. The broad categories of numbers used by us are – Natural Numbers, Whole Numbers, Integers, Rational Numbers, and Irrational Numbers. The set of Real Numbers consists of all the other categories.

Recommended Reading

FAQs

What is Decimal Number System?

A decimal number system uses $10$ symbols commonly known as digits. The digits used in decimal number system are $1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $9$, and $0$.

Where is Decimal Number System used?

We use the decimal number system in our day-to-day life, whether it is money, measurements like length/distance, weights, or capacities.

What is Decimal Number System also called?

The decimal number system is also called a base $10$ number system since it uses $10$ symbols or digits. All the numbers in the decimal number system are formed from the digits $1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $9$, and $0$.

What are the four important properties of decimal numbers?

The four important properties of decimal numbers are commutative property, associative property, distributive property, and identity property.

What are different types of decimal numbers?

There are many different categories of decimal numbers. But broadly decimal numbers are categorized as natural numbers, whole numbers, integers, rational numbers, irrational numbers, and real numbers.

Which of the sets – natural numbers and integers is smaller?

The set of natural numbers is smaller compared to the set of integers. The hierarchy of different sets of decimal numbers from highest to lowest is real numbers ( = rational numbers + irrational numbers) > integers > whole numbers > natural numbers.

Is $0$ present in all the different sets of decimal numbers?

$0$ is present in all the different sets of decimal numbers except the set of natural numbers.

Leave a Comment