Page 10 - Maths Skills - 7

8 Maths

INTRODUCTION
We have already learnt about integers in the previous class. With the help of this chapter, we will learn little more
about the different aspects and properties of integers.

INTEGERS
A combined set of negative numbers and whole numbers is called integers, it is denoted by ‘I’ or ‘Z’.

Thus Z = {...., – 4, – 3, – 2, – 1, 0, 1, 2, 3, 4, ...}
As you see in this set, all the natural numbers are positive integers and others are negative integers. 0 (zero) is

neither positive nor negative.

REPRESENTATION OF INTEGERS ON A NUMBER LINE

Negative Integers Positive Integers

– 6 – 5 – 4 – 3 – 2 – 1 0 1 2 3 4 5 6

Fig.
Draw a line and mark some points at equal distance on it as shown in Fig. Mark a point as zero on it. Points to the
right of zero are positive integers and are marked + 1, + 2, + 3, etc. or simply 1, 2, 3, etc. Points to the left of zero
are negative integers and are marked – 1, – 2, – 3, etc.

Let’s Attempt

Example 1: By looking at the number line, answer the following questions.
(i) Which integers lie between – 9 and – 3?

(ii) Which is the largest integer and the smallest integer among them?
Solution: (i) Integers between – 9 and – 3 are – 8, – 7, – 6 – 5, – 4.

(ii) The integer – 4 is the largest and – 8 is the smallest. – 9 – 8 – 7 – 6 – 5 – 4 – 3

Example 2: (i) One button is kept at – 4 on the number line. In which direction and how many steps should
we move to reach at – 10?
(ii) Which number will we reach on a number line if we move 4 steps to the right of – 7?

Solution: (i) We have to move six steps to the left of – 4.
(ii) We reach – 3 when we move four steps to the right of – 7.

Exercise 1.1

1. Represent the following numbers as integers with appropriate signs.
(i) An aeroplane is flying at a height of two thousand metres above the ground.

(ii) A submarine is moving at a depth, eight hundred metres below the sea level.
(iii) A deposit of rupees two hundred.

(iv) Withdrawal of rupees seven hundred.