Ques 1: Fill in the blanks:
(a) 30 ÷ ________ = 3
(b) – 89 ÷ ________ = 89
(c) ________ ÷ 1 = – 205
(d) ________ × (–12) = 120
(e) 24 + 12 ÷ 4 – 5 × 3 = ________
Answer 1:
(a) 10
Solution:
30/10 = 3
(b) –1
Solution:
– 89 ÷ -1 = 89
(c) –205
Solution:
When a number is divided by 1, the quotient is the number itself.
(d) –10
Solution:
let blank be X
X x(-12)=120
X=120/-12
X=-120/12
X=-10
= -10
(e) 12
Solution:
24+12 ÷ 4-5×3
=24+3-5×3
=24+3-15
=27-15
=12
Ques 2: Find the value of P, if p × (–9) = 135
View AnswerAns 2: P = –15
Solution:
We can simply find the value of p by solving the linear equation by transposing the terms.
p× (-9) = 135
Transposing -9 from LHS to RHS, we get
p = 135/ (-9)
Simplifying 135/(-9), we get
p = -15
∴ The value of p is (-15).
Hence, the value of p if p× (-9) = 135 is (-15).
Ques 3: The additive inverse of zero (0) is ________.
View AnswerAns 3: 0
Solution: The additive inverse of a number is an integer that gives 0 as the sum when added.
E.g. - Let the required number be 3.
Then its additive inverse is -3.
since, -3 + 3 = 0
The additive inverse of 0 would be 0.
As, 0 + 0 = 0.
Ques 4: Match the properties of Integers:
(a) Distributive law over addition | (i) a + 0 = a = 0 + a |
(b) Associative law for multiplication | (ii) a + b = b + a |
(c) Additive Identity | (iii) (a × b) × c = a × (b × c) |
(d) Commutative law over addition | (iv) a × 1 = 1 × a = a |
(e) Multiplicative Identity | (v) a × (b + c) = a × b + a × c |
Ans 4:
(a) - (v)
(b) - (iii)
(c) - (i)
(d) - (ii)
(e) - (iv)
Ques 5: Use the sign of >, < or = in the box to make the statement true.
(a) 25 – 40 + 10 25 – 40 – 10
1. 25 - 40 + 10
View AnswerAns: >
Sol: We work from left to right:
25 - 40 + 10
25 - 40 = -15 , So now we have -15 + 10
-15 + 10 = -5
Solving, 25 – 40 – 10
We work from left to right:
25 - 40 = -15
So now we have -15 - 10 = - 25
-5 > - 25
(b) (–9) + (–6) (–9) – (–6)
View AnswerAns: <
Sol:
(–9) + (–6) = -15
(–9) – (–6) = -3
-15< -3
(c) 35 + (–70) – (–35) (–24) – (15) + 39
View AnswerAns: =
Sol: We work from left to right:
35 + (–70) = - 35
So, - 35 - (-35) = 0
Solving, (–24) – (15) + 39
(–24) – (15)= -39
-39+ 39 = 0
Ques 6: Evaluate :
(a) (–1) × (–2) × (–3) × (–4) × (–5)
(b) 795 × (–25) + (–795) × 75
(c) (–59) × (–19) + 59
Ans6:
(a) –120
Sol:
-1×(-2)×(-3)×(-4)×(-5)
= -2×(-12)×(-5)
= -24×(-5)
= -120
(b) –79500
Sol: 795×(-25)+(-795)×75
= -19875+(-59625)
= -19875-59625
= -79500
(c) 1180
Sol: -59×(-19)+59
= 1121+59
= 1180
Ques 7: An elevator descends into a mine shaft at the rate of 7m/min. If the descent starts from 5m above the ground level, how long will it take to reach – 205m?
View AnswerAns7. 30 min.
Sol:
Total distance to be travelled = 5 m + 205 m = 210 m
Speed of descent = 7 m / min
Total Time = Distance / Speed
= 210 m / (7 m/min)
= 30 min
Ques 8: With the help of number line find how much greater is the number 3 than –3.
View Answer
Ans8:
Ques 9: The sum of two integers is –1500. One of the numbers is 599. Find the other number.
View AnswerAns9: –2099
Sol: Let the number be X
the other number = 599
599 + X = 1500
X = 1500 - 599
X = 901
Ques 10: Write the answer in True/False :
(a) When 0 is divided by an integer, the quotient is zero.
(b) The product of an integer and 1 is an integer.
(c) When an integer is divided by itself, the quotient is 1.
Ans 10: (a) True
(b) True
(c) True
Ques 11: The product of two integers is –160. If one of them is 20, find the other.
View AnswerAns 11: –8
Sol:
Let the number be X
X * 20=-160
X =-160/20
X=-8
Ques 12: What integers should be multiplied by (–12) to becomes –300.
View AnswerAns 12: 25
Sol:
Let the integer be "a"
According to question,
(-12) × a = - 300
a = - 300 / - 12
a = 300 /12
a = 25
Required number = 25
Ques 13: Pallavi got a scholarship of Rs.1000 from her school. If she gives 550 for the help of flood relief, find the balance amount with her.
View AnswerAns 13: ₹ 450
Sol:
Total Amount = 1000
Rupees given for help = 550
Remaining balance of Pallavi= 1000-550 = 450
Ques 14: A building has 21m in height. A monkey can climb 3m in one jump. In how many jumps, would the monkey reach at the top of the building?
View AnswerAns 14: 7
Sol: If the monkey could jump 3m once then he would have to jump 7 times to reach at top of the building as 7*3 = 21
Ques 15: Find solutions for the following problems:
a) Both numbers are less than 10.
The distance between the two numbers on the number line is 14.
b) Both numbers are greater than -15 and less than 5
One number is 6 greater than the other number.
c)The numbers are opposites.
The distance between the two numbers on the number line is 18.
d) One number is -35.
The distance between the two numbers on the number line is 20.
e) The first number is the opposite of -17.
The second number is less than the first number.
The distance between the two numbers on the number line is 9.
Sol: These questions can be easily solved using the number line.
a) There can be many solutions, one solution will be 7 and -7. They both are less 10 and difference is 14
Other solution could be -11 and 3.They both are less 10 and difference is 14
b) There can be many solutions, one solution will be -14 and -8.
Other solution could be -13 and -7.
c) This one will have unique solution. The number will be -9 and 9. Both are opposites and distance between them is 18
d) There can two solutions, one solution will be -55 and another one is -15
e) There can be one solution only. the solution is 17 and 8.
Ques 16: Fill in the blanks using different operations :
View AnswerAns16:
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1. What are integers? |
2. How do you add integers? |
3. What is the difference between positive and negative integers? |
4. How do you subtract integers? |
5. Can integers be fractions or decimals? |
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