7th Maths : Term 1 Unit 1 : Number System : Exercise 1.1 : Fill in the blanks, Say true or false, Objective type questions, Text Book Back Exercises Questions with Answers, Solution

**Exercise
1.1**

**1.
Fill in the blanks**

(i) (−30) + ** 90** = 60

(ii) (−5) + ** –95** = −100

(iii) (−52) + (−52) = __–104__

(iv) ** 22** + (−22) = 0

(v) ** 140** + (−70) = 70

(vi) 20+80+ ** (–100)** =0

(vii) 75 + (−25) = __50__

(viii) 171+ ** (–171)** = 0

(ix) [(−3)+ (−12)] + (−77) = ** ( –3)** + [(−12)+
(−77)]

(x) (−42)+ [ ** 15** + (−23)] = [

**2.
Say true or false.**

(i) The additive inverse of (–32) is (–32)**(False)**

(ii) (−90)+( −30) = 60**(False)**

(iii) (−125)+25 = −100**(True)**

**3.
Add the following**

**(i)
8 and –12 using number line**

**8 + 12 = –4**

**(ii)
(–3) and (–5) using number line**

**(–3) +(–5) = –8**

(iii)
(−100)+ (−10)** =** **–110**

(iv)
20 + (−72)** = –52**

(v)
82 + (−75)** = 7**

(vi)
−48 + (−15)** = –63**

(vii)
−225 + (−63)** = –288 **

** **

**4.
Thenmalar appeared for competitive exam which has negative scoring of 1 mark
for each incorrect answer. In paper I she answered 25 questions incorrectly and
in paper II, 13 questions incorrectly. Find the total reduction of marks.**

Total reduction of marks = (–25) + (–13)

= –38

** **

**5.
In a quiz competition, Team A scored +30,–20, 0 and team B scored –20, 0, +30
in three successive rounds. Which team will win? Can we say that we can add
integers in any order?**

TeamAscored = +30 – 20 + 0 = +10

Team B scored = –20 + 0+ 30 = +10

Team A = Team B

Yes, it can be added in any order.

** **

**6.
Are (11 + 7) +10 and 11 + (7 +10) equal? Mention the property.**

(11+7) + 10 = 18 + 10 = 28

11 + (7+10) = 11 + 17 = 28

(11+7) + 10 = 11 + (7+10)

Both are equal

Associative property under addition

** **

**7.
Find 5 pairs of integers that add up to 2.**

0 + 2, 1 + 1=2, –1+3 = 2, –2
+ 4 = 2, –3 + 5 = 2

** **

__Objective type questions__

**8.
The temperature at 12 noon at a certain place was 18 º at above zero. If it
decreases at the rate of 3 º per hour at what time it would be 12 º below zero?**

(i) 12 mid night

(ii) 12 noon

(iii) 10 am

(iv) 10 pm

*Answer :***(iv) 10 pm**

**9.
Identify the problem with negative numbers as its answer:**

(i) −9+(−5)+6

(ii) 8+(−12)−6

(iii) −4+2+10

(iv) 10+(–4)+8

*Answer :***–9 – (–5) + 6**

**10.
(−10)+ (+7) = ____**

(i) +3

(ii) –3

(iii) −17

(iv) +17

*Answer :***(ii) –3**

**11.
(−8)+10 + (−2) = ____**

(i) 2

(ii) 8

(iii) 0

(iv) 20

*Answer :***(iii) 0**

**12.
20 + (−9)+ 9 = ____**

(i) 20

(ii) 29

(iii) 11

(iv) 38

*Answer :***(i) 20**

**ANSWERS**

**ANSWERS**

**Exercise 1.1 **

1. (i) 90 (ii) −95 (iii) −104
(iv) 22 (v)140 (vi) −100 (vii) 50 (viii) –171 (ix) −3 (x) 15, −42 , −23

2. (i) False (ii) False (iii)
True

3. (i) −4 (ii) −8 (iii) −110 (iv)
–52 (v)7 (vi) −63 (vii) −288

4. –38

5. Team A = Team B (yes, it can
be added in any order)

6. Both are equal. Associative
property under Addition

7. 0 + 2 , 1 + 1 = 2 , −1 + 3 ,
−2 + 4 , −3 + 5 (any pair)

**Objective type questions**

8. (iv) 10 pm

9. (i) –9+(–5)+6

10.(ii) –3

11. (iii) 0

12. (i) 20

Tags : Questions with Answers, Solution | Number System | Term 1 Chapter 1 | 7th Maths , 7th Maths : Term 1 Unit 1 : Number System

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7th Maths : Term 1 Unit 1 : Number System : Exercise 1.1 (Properties of Addition) | Questions with Answers, Solution | Number System | Term 1 Chapter 1 | 7th Maths

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