Basics of Number System for Competitive Exams. Number system is the way of writing numbers. Numerals or symbols are represented as a number depending upon the number system. Binary, Octal, Decimal, Hexadecimal, etc. are some popular number systems.
Decimal Number System
Decimal number system is the most commonly used and also called the Hindu-Arabic number system.
There are total ten digits (0to 9) used in the decimal number system. So it is a base 10 number system.
Two types of values of a digit in a number:
(1) Face Value – Face Value is the value of the digit itself.
(2) Place Value – Place value depends upon the position of the digit in the number.
Every place in a number is 10 times more to the immediate right place.
Representation of a Number
(1) Standard Form:
Example: 1234.5678
(2) Expanded Form:
Example: 1000+200+30+4+0.5+0.06+0.007+0.0008
(3) Word Form
Example: One thousand two hundred thirty four and (point) five thousand six hundred seventy eight ten thousandth
