7th Maths : Term 1 Unit 1 : Number System : Exercise 1.3 : Fill in the blanks, Say true or false, Find the value of the following, Objective type questions, Text Book Back Exercises Questions with Answers, Solution

**Exercise 1.3**

**1.
Fill in the blanks**

(i) −80 × ** 1** = −80

(ii) (−10) × ** –2** = 20

(iii) (100) × ** –5** = −500

(iv) ** 5** × ( −9) = −45

(v) ** 0** × 75 = 0

**2.
Say true or false**

(i) (−15)× 5 = 75**(False)**

(–15) × 5 = –75. So (–15) × 5 = 75

(ii) (−100)× 0 × 20 = 0**(True)**

(iii) 8×(−4)=32**(False)**

8 × (–4) = –32. So 8 × (–4)
= 32

**3.
What will be the sign of the product of the following.**

**(i)
16 times of negative integer.**

Positive

**(ii)
29 times of negative integer.**

Negative

** **

**4.
Find the product of**

**(i)
( −35) × 22 **

(–35) × 22 = –770

**(ii)
(−10) ×12 × (−9) **

(–10) × 12 × (–9) =1080

**(iii)
( −9) × ( −8) × ( −7) × ( −6)**

(–9) × (–8) × (–7) × (–6)

72 × 42 = 3024

**(iv)
( −25) × 0 × 45 × 90 **

[(–25) × 0] × (45 × 90) = 0
× 4050 = 0

**(v)
(−2) × (+50) × (−25) × 4**

[(–2) × (+50)] × (–25) × 4

–100 × –100 = 10,000

** **

**5.
Check the following for equality and if they are equal, mention the property.**

**(i)
(8 − 13) × 7 and 8 − (13 × 7)**

(8 – 13) × 7 = –5 × 7 = –35

8 – (13 × 7) = 8 – 91 = –83

(8–13) × 7 ≠ 8 – (13 × 7)

They are not equal.

**(ii)
[(−6) − (+8)] × (−4) and ( −6) −[ 8 × ( −4)]**

[(–6) – (+8)] × (–4) = (–6 – 8) × (–4)

= 14 × –4 = 56

(–6) – (8 × (–4)] = (–6) – (–32)

= –6 + 32 = 26

[(–6) – (+8)] × (–4) ≠ (–6) – (8 × 4 – 4)

They are not equal.

**(iii)
3 × [(−4) + ( −10)] and [ 3 × (−4) + 3 × (−10)]**

3 × [(–4) + (–10)] = 3 × [–14] = –42

[3 × (–4) + 3 × (–10)] = –12 – 30 = –42

3 × [(–4) + (–10)] = [3 × (–4) + 3 × (–10)]

They are equal.

** **

**6.
During summer, the level of the water in a pond decreases by 2 inches every
week due to evaporation. What is the change in the level of the water over a
period of 6 weeks?**

Level of water decreases in 1 week = 2 inches

Level of water decreases in 6 weeks = 6 × 2 = 12 inches

Level of water deceases in 6 weeks = 12 inches

** **

**7.
Find all possible pairs of integers that give a product of −50 .**

(–5 × 10), (–10 × 5), (2 ×
–25), (–2) × 25, (–1) × 50, 1 × (–50)

** **

__Objective
type questions__

**8.
Which of the following expressions is equal to –30.**

(i) –20 – (–5* *×* *2)

(ii) (6* *×* *10) – (6* *×* *5)

(iii) (2* *×* *5) + (4* *×* *5)

(iv) (–6)*
*×* *(+5)

*Answer :***(iv) (–6) × (+5)**

**9.
Which property is illustrated by the equation: (5 × 2) + (5 × 5) = 5 × ( 2 + 5)**

(i) commutative

(ii) closure

(iii) distributive

(iv) associative

*Answer :***(iii)
distributive property**

**10.
11×(–1) = _____**

(i) –1

(ii) 0

(iii) +1

(iv) –11

*Answer :***(iv) –11**

**11.
(−12)× (−9) = _____**

(i) 108

(ii) –108

(iii) +1

(iv) –1

*Answer :***(i) 108**

__ANSWERS__

**Exercise 1.3 **

1. (i) 1 (ii) −2 (iii) −5 (iv) 5
(v) 0

2. (i) False (ii) True (iii)
False 3. (i) '+' (ii) '–'

4. (i) −770 (ii) 1080 (iii) 3024
(iv) 0 (v) 10,000

5. (i) Not equal (ii) Not equal
(iii) Equal ; distributive property of multiplication over addition

6. Decrease of 12inches

7. (−5×10),(−10 × 5), 2 25
,(−2)×25, ,(−1)× 50 ,(−50)×1

**Objective type questions **

8. (iv) (–6) × (+5)

9. (iii) distributive

10. (iv) –11

11. (i) 108

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 1.3 (Multiplication of Integers) | Questions with Answers, Solution | Number System | Term 1 Chapter 1 | 7th Maths

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