Page 23 - Revised Maths Wisdom Class - 6
P. 23
2 The Other Side of Zero
CHAPTER OUTLINES
● Introduction ● Credit and Debit Concepts ● Operations on Integers
● Negative Numbers ● Representation of Integers on Number line ● Brahmagupta’s Rules
● Absolute Value of an Integer ● Ordering of Integers ● Explorations with Integers
RECALL
● Natural numbers are a set of numbers denoted by N = {1, 2, 3, ... n}.
● Whole numbers are a set of numbers denoted by W = {0, 1, 2, 3, ... n}.
● The smallest natural number is 1 and the smallest whole number is 0.
● We cannot find the largest natural or whole number as they are limitless.
● All natural numbers are whole numbers but all whole numbers are not the natural numbers.
Introduction
Raj was reading a newspaper and was puzzled to see a tabular Lowest temperatures ever recorded
information as shown here:
Country/Region Temperature (°C)
He is well aware of the facts and properties of natural numbers and World Antarctica –89.2
whole numbers but these numbers with ‘–’ sign were new to him. Dome A –82.5
Let us understand what these numbers with ‘–’ sign stands for.
South Pole –82.8
Antarctica is the coldest region on earth with temperature falling Russia –68
89.2°C below 0°C, i.e., –89.2°C. But there is no number in the set of Bangladesh 2.8
whole numbers which is preceded by negative sign ‘–’. This number China –52.3
is less than zero. Let us learn more about such number.
India –50
Negative Numbers
You must have come across statements like, the temperature is –15°C, the submarine is 250 m below sea level
etc. This all represents a new number system that takes negative numbers into account. This set is called Integers.
Thus, integers are a set of numbers denoted by I or Z and is written as
Z = {..., – 4, –3, –2, –1, 0, 1, 2, 3, ...}
where ... –4, –3, –2, –1 are negative integers and 1, 2, 3, 4, ... are called positive integers. The number 0 is neither
positive integer nor negative integer.
Remember!er!
Rememb
Zero is an integer. ‘–’ sign with negative integer does not indicate subtraction.
All natural numbers are positive integers. While writing positive integers ‘+’ sign is omitted.
