Page 115 - ICSE Math 5

Example 1: Write the opposites of the following.
(a) Decrease in weight (b) 80 km east

(c) Loss of ` 500 (d) 20 m below sea level
Solution: (a) Increase in weight (b) 80 km west

(c) Profit of ` 500 (d) 20 m above sea level
Example 2: Represent the following as integers by using appropriate signs.

(a) Depth of 15 m (b) 7°C below 0°C (c) A withdrawal of ` 9,575
Solution: (a) –15 m (b) –7°C (c) – ` 9,575

Example 3: Represent the following integers on a number line.
(a) +5 (b) 0 (c) –7 (d) –9

Solution: The integers given in part (a), (b), (c) and (d) are represented by letters A, B, C and
D, respectively on the following number line.
D C B A

–10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10

Predecessor and Successor of an Integer

We already know that a number that is one less than a given number is called its predecessor and
a number that is one more than the given number is called its successor.
Similarly, an integer that is one less than the given integer is called its predecessor and an integer
that is one more than the given integer is called its successor. Thus, on the number line, each
integer is the predecessor of the integer that is on the right of it. For example, 1 is the predecessor
of 2, 0 is the predecessor it 1, –1 is the predecessor of 0, and so on.

In the same way, each integer is the successor of the integer that is on the left of it. For example,
–3 is the successor of –4, –2 is the successor of –3, –1 is the successor of –2, and so on.
Example 4: Look at the given number line and write the predecessor and successor of the
following integers.

–10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10

(a) –2 (b) 3 (c) 9 (d) –6

Solution: Integer Predecessor Successor

(a) –2 –3 –1

(b) 3 2 4

(c) 9 8 10

(d) –6 –7 –5

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