Page 31 - Revised Maths Wisdom Class - 6

The Other Side of Zero 29

8 – 6 = 8 + (– 6) = 2

– 2 ≠ 2
3. Associative Property: For any integers a, b and c. 4. Property of Zero: If a is any integer, then

(a – b) – c ≠ a – (b – c) a – 0 = a
Thus, subtraction is not associative for integers. For example, – 6 – 0 = – 6.

For example, (6 – 3) – (–7) = 6 – 3 + 7 = 10
6 – [3 – (–7)] = 6 – 10 = – 4
10 ≠ – 4

ILLUSTRATIONS

Example 1: Find the value of –5 – (–3) using number line.
Solution: –5 – (–3) = –5 + 3 as additive inverse of –3 is 3.

On the number line, starting from –5 we will move 3 steps towards right to get the required number.

–8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8
Hence, –2 is the required number.

Example 2: Subtract –13 from –29.
Solution: –29 – (–13)
= –29 + 13 [additive inverse of –13 is 13]

= –16
Example 3: Evaluate: –31 – (–19) – (–1) –4 Check: –19 – (–119) = –19 + 119 = 100
Solution: –31 – (–19) – (–1) –4

= –31 + 19 + 1 – 4 = –35 + 20 = –15
Example 4: What should be subtracted from –19 to get 100?
Remember!er!
Solution: As per the question, Rememb
– 19 – ? = 100 › + (+p) = +p, – (–p) = +p
The required number will be –100 – 19 = –119 › + (–p) = –p, – (+p) = –p

Exercise 2C
Exercise 2C
1. Using number line, find the value of:
(a) –6 – (–3) (b) 8 – (–3) (c) 11 – (–4)

2. Subtract the following:
(a) –16 from 10 (b) 89 from –111 (c) –999 from 1000 (d) 863 from 984
(e) –11 from –191 (f) –179 from 3971 (g) 0 from –199 (h) –1 from 999

3. Is 16 – (–31) = –31 – 16?
4. Find the difference between a temperature of 16°C above 0°C and a temperature of 10°C below zero.