Math-Magic Solutions for Class-4, Chapter-6: The Junk Seller
The Junk Seller deals with the concept of cost, priceand price . This chapter have exercises on rate chart, cost price, selling price, profit. The solutions for Math-Magic Chapter-6 have been created and verified by our experienced subject matter experts, according to the CBSE syllabus and guidelines of NCERT. For practice, our subject matter experts have created very interactive, activity-based, and Image-based worksheets on these topics to enhance learning.
Download the NCERT Solutions for The Junk Seller in PDF
The Junk Seller
First guess the answer and then calculate: a) 37 × 18
Step 1: The guessed answer is 40 × 20 = 800.
37 × 18 is calculated as:
Step 2: Add 300, 240, 70, and 56.
300 + 240 + 70 + 56 = 666
Therefore, 37 × 18 = 666.
What about you? Do you also find Maths difficult?
Maths is a very interesting and amusing subject. Answer the question based on your experience. The answer may vary from student to student.
What is the most difficult thing in your Maths book?
Recall whatever you have studied in your Maths book and write the topic in which you faced the most difficulty. The answer may vary.
c) 69 × 52
Step 1: The guess answer is 60 × 50 = 3000.
69 × 52 is calculated as:
Step 2: Add 3000, 120, 450, and 18.
3000 + 120 + 450 + 18 = 3588
Therefore, 69 × 52 = 3588.
What do you think is the easiest lesson?
Recall whatever you have studied in Maths lessons and write the lesson which was the easiest for you. The answer may vary.
And in a month?
Amount he earns in one day is Rs 30. Number of days in a month is 30.
Multiply 30 by 30 to get the amount he will earn in a month.
30 × 30 = 900
Therefore, he will earn Rs 900 in a month.
How did you get the answer? Discuss.
When 30 is multiplied by 3 the answer is 90. Therefore, when 30 is multiplied by 30 the answer will be 900.
d) 77 × 55
Step 1: The guessed answer is 80 × 50 = 4000.
77 × 55 is calculated as:
Step 2: Add 3000, 120, 450, and 18.
3000 + 120 + 450 + 18 = 3588
Therefore, 69 × 52 = 3588.
So, how much money does she earn for 63 kg?
Step 1: She earns Rs 2 on selling 1 kg plastic. Therefore, she will earn 63 × 2 on selling 63 kg plastic.
63 × 2 can be calculated as:
Step 2: Add 120 and 6.
120 + 6 = 126
Therefore, she will earn Rs 126.
e) 142 × 5
Step 1: The guessed answer is 140 × 5 = 700.
142 × 5 is calculated as
Step 2: Add 500, 200, and 10.
500 + 200 + 10 = 710
Therefore, 142 × 5 = 710.
Kiran sells 32 kg iron. How much money will Dinu pay for 32 kg iron?
Step 1: The amount Dinu pay for 1 kg iron is Rs 14. Therefore, the amount he will pay for 32 kg iron is Rs 14 × 32.
14 × 32 can be calculated as:
Step 2: Add 300, 120, 20 and 8.
300 + 120 + 20 + 8 = 448
Thus, Dinu paid Rs 448.
f) 382 × 3
Step 1: The guessed answer is 380 × 3 = 1140.
382 × 3 is calculated as:
Step 2: Add 900, 240 and 6.
900 + 240 + 6 = 1146
Therefore, 382 × 3 = 1146.
Kiran buys 1 kg iron for Rs 12, but sells it for Rs 14. How much does she earn when she sells 32 kg iron?
Step 1: Kiran buys 1 kg iron for Rs 12 and sells it for Rs 14. Subtract 12 from 14 to get the amount she earned on selling 1 kg iron.
14 – 12 = 2
Step 2: She earned Rs 2 on selling 1 kg iron. Therefore, she will earn Rs 2 × 32 on selling 32 kg iron.
2 × 32 can be calculated as:
Step 3: Add 60 and 4.
60 + 4 = 64
Therefore, she will earn Rs 64.
g) 2 × 175
Step 1: The guessed answer is 2 × 180 = 360.
2 × 175 is calculated as:
Step 2: Add 200, 140, and 10.
200 + 140 + 10 = 350
Therefore, 2 × 175 = 350.
h) 4 × 206
Step 1: The guessed answer is 5 × 200 = 1000.
4 × 206 is calculated as:
Step 2: Add 800 and 24.
800 + 24 = 824
Therefore, 4 × 206 = 824
Later she paid Rs 919 to the junk collectors. When she sold the junk she got these notes and coins from Dinu.
Now you make a record in her diary. Find out how much she earned this time.
She received:
• 5 notes of Rs 100 = Rs 500
• 1 note of Rs 50 = Rs 50
• 9 notes of Rs 20 = Rs 180
• 18 notes of Rs 10 = Rs 180
• 28 coins of Rs 5 = Rs 140
Therefore, the total amount she received is:
100 + 50 + 180 + 180 + 140 = 1050
The amount she paid is Rs 919.
Amount she gained = 1050 – 919 = 131.
The record in the dairy is given below:
How much money will Dinu pay for 4 kg brass?
Step 1: The cost of 1 kg brass is Rs 180. Therefore, the cost 4 kg of brass will be 180 × 4.
180 × 4 is calculated as:
Step 2: Add 400 and 320.
400 + 320 = 720
Therefore, Dinu will pay Rs 720 for 4 kg brass.
Find out: how much for a cup of tea?
Ask people and find out the cost of a cup of tea
At a tea stall _______
At a hotel ________
Do it by yourself. Answers may vary. The cost of a cup of tea is different at different places. In general, the cost of a cup of tea at a tea stall is Rs 10 and at a hotel is Rs 25.
If a person who runs a tea stall earns Rs 30 in a day, how much will he earn in 10 days? __________
The amount he earns in a day is Rs 30. Multiply 30 by 10 to get the amount he will earn in 10 days. 30 × 10 = 300 Therefore, he will earn Rs 300 in 10 days.
Find out: what is a loan? Have you ever heard of someone taking a loan? For what? How much loan was taken? How much money was paid back?
A loan is the money borrowed from someone or the bank. The money taken will have to be returned after a certain period of time with some addition amount called interest.
Try to think if you have ever heard about the term loan and if yes, then answer the given questions.
Hariya and Babu want to buy a handcart for Rs 300. Hariya has taken a loan of Rs 300 from a bank for six months. He will pay Rs 51 every month to the bank. But Babu hastaken a loan of Rs 300 from Chunnilal. After six months, he will pay back Rs 360.
Who has to pay back more- Hariya or Babu?
Hariya pay Rs 51 every month for 6 months. Multiply 51 by 6 to get the total amount he will pay pack.
51 × 6 = 306
Therefore, Hariya will pay Rs 306 but Babu will pay Rs 360 which is more than 306.
Thus, Babu has to pay back more.
I have 9 rickshaws of my own. I give the rickshaws on rent, each for Rs 20 a day. On Sundays, I do not take any money for them.
How much does Kiran earn from 9 rickshaws in a Day?
For 1 rickshaw she gets Rs 20 per day.
Step 1: Multiply 20 by 10 to get the amount she gets for 10 rickshaws.
20 × 10 = 200
Step 2: Subtract 20 from 200 to get the amount she will get for 9 rickshaws.
200 – 20 = 180
Therefore, she will get Rs 180 from 9 rickshaws in a day.
In a week how much does Kiran earn from one rickshaw?
Step 1: There are 7 days in a week. Multiply 20 by 7 to get the amount she will earn in 7 days.
20 × 7 = 140
Step 2: She does not take money on Sunday. Subtract 20 from 140 to get the amount she will get in a week from 1 rickshaw.
140 – 20 = 120
Therefore, she will earn Rs 120
Do it mentally and write the answers.
2 × 6 = ______
20 × 6 = ______
2 × 60 = ______
3 × 42 = ______
4 × 80 = ______
4 × 81 = ______
9 × 25 = ______
31 × 9 = ______
The correct answers are:
2 × 6 = 12
20 × 6 = 120
2 × 60 = 120
3 × 42 = 126
4 × 80 = 320
4 × 81 = 324
9 × 25 = 225
31 × 9 = 279
Kiran has bought some junk from junk collectors. Look up the rate list to see today’s rates. Help Kiran to find out the cost of the junk.
How much will Kiran pay for 31 kg newspaper?
Step 1: The cost of 1 kg newspaper is Rs 5. Multiply 30 by 5 to get the cost of 30 kg newspaper.
30 × 5 = 150
Step 2: Add 150 and 5 to get the cost of 31 kg newspaper.
150 + 5 = 155
Therefore, the cost of 31 kg newspaper is Rs 155
The How much will Kiran pay for 42 kg newspaper?
Step 1: The cost of 1 kg newspaper is Rs 5. Multiply 40 by 5 to get the cost of 40 kg newspaper.
40 × 5 = 200
Step 2: Multiply 2 by 5 to get the cost of 2 kg newspaper.
2 × 5 = 10
Step 3: Add 200 and 10 to get the cost of 42 kg newspaper.
200 + 10 = 210
Therefore, the cost of 42 kg newspaper is Rs 210
Also find the cost of:
a) 22 kg of plastic
Step 1: The cost of 1 kg plastic is Rs 10. Multiply 10 by 20 to get the cost of 20 kg plastic.
20 × 10 = 200
Step 2: Multiply 2 by 10 to get the cost of 2 kg plastic.
2 × 10 = 20
Step 3: Add 200 and 20 to get the cost of 22 kg plastic.
200 + 20 = 220
Therefore, the cost of 22 kg plastic is Rs 220.
Also find the cost of:
b) 23 kg of waste paper
Step 1: The cost of 1 kg waste paper is Rs 4. Multiply 4 by 20 to get the cost of 20 kg waste paper.
20 × 4 = 80
Step 2: Multiply 3 by 4 to get the cost of 3 kg waste paper.
3 × 4 = 12
Step 3: Add 80 and 12 to get the cost of 23 kg waste paper.
80 + 12 = 92
Therefore, the cost of 23 kg waste paper is Rs 220
c) 12 kg of iron
Step 1: The cost of 1 kg iron is Rs 12. Multiply 10 by 12 to get the cost of 10 kg iron.
10 × 12 = 120
Step 2: Multiply 2 by 12 to get the cost of 2 kg iron.
2 × 12 = 24
Step 3: Add 120 and 24 to get the cost of 12 kg iron.
120 + 24 = 144
Therefore, the cost of 12 kg iron is Rs 220.
Guess the total money Kiran will pay to the junk collectors. Will it be
-More than 600?
-Less than 600?
Amount she pays for 42 kg newspaper is Rs 210.
Amount she pays for 22 kg plastic is Rs 220.
Amount she pays for 23 kg waste paper is Rs 92.
Amount she pays for 12 kg iron is Rs 144.
Add 210, 220, 92, and 144 to get the total money she paid.
210 + 220 + 92 + 144 = 666.
Therefore, she pays more than 600.
Kiran bought 1kg plastic for Rs 10, but sold 1 kg plastic for Rs 12. How much money does she earn on selling 1 kg plastic?
Kiran bought 1 kg plastic for Rs 10. She sold 1 kg plastic for Rs 12. Subtract 10 from 12 to get the amount she earned.
12 – 10 = 2
Therefore, on selling 1 kg of plastic she earns Rs 2.
I bought 1 kg newspaper for Rs 5, but sold it for Rs 6. How much do I earn by selling 152 kg of newspaper?
Step 1: Cost of 1 kg newspaper is Rs 5 and selling price of 1 kg newspaper is Rs 6.
Subtract 5 from 6 to get the amount she earned on selling 1 kg newspaper.
6 – 5 = 1
Step 2: She earned Rs 1 on selling 1 kg newspaper. Multiply 1 by 152 to get the money she will earn on selling 152 kg of newspaper.
1 × 152 = 152.
Therefore, she will earn Rs 152.
b) 45 × 24
Step 1: The guessed answer is 40 × 25 = 1000.
45 × 24 is calculated as:
Step 2: Add 800, 160, 100, and 20.
800 + 160 + 100 + 20 = 1080
Therefore, 45 × 24 = 1080.
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