# NCERT Solutions for Class 4 Mathematics Unit-6 The Junk Seller

**NCERT Textbook Page 60**

**1. What about you? Do you also find Maths difficult?**

**Ans.** No. I do not find Maths difficult. It becomes easy if it is practised well regularly.

**2. What is the most difficult thing in your Maths book?**

**Ans.** Nothing, all topics look easy to me.

**3. What do you think is the easiest lesson?**

**Ans**. All lessons are of equal level. This depends upon a lot of practice of maths.

**NCERT Textbook Page 61**

**Find out: How much for a cup of tea?**

**1. Ask people and find out the cost of a cup of tea –**

** • At a tea stall**

**Ans.** At a tea stall a cup of tea costs Rs 3.

**• At a hotel**

**Ans.** At a hotel a cup of tea costs Rs 5.

**2. If a person who runs a tea stall earns ? 30 a $ay, how much will he earn in 10 days?**

**Ans.**

Earning in 1 day = Rs 30 x 1

Therefore, earning in 2 days = Rs 30 x 2

Earning in 3 days = Rs 30 x 3

And so on_______

Earning in 10 days = Rs 30 x 10 = 300

**•And in a month?**

**Ans.**

A month has 30 days

If earning in 1 day = Rs 30

Therefore, earning in 30 days = Rs 30 X 30 = Rs 900.

**FindOut: What is a Loan?**

**1. Have you ever heard of someone taking a loan? For what?**

**Ans**.I heard a person took loan. He took loan to start his shop.

**2. How much loan was taken?**

**Ans.** He took Rs 10,000.

**3. How much money was paid back?**

**Ans**.He paid back Rs 11,000 after one year.

**4. Who has to pay back more-Hariya or Babu?**

**Ans**.Hariya has to pay Rs 51 every month for six months.

Total money he has to pay = 51 x 6 = Rs 306 Babu has to pay Rs 360

Hence, Babu will have to pay back more money.

**NCERT Textbook Page 62**

**1. How much does Kiran earn from 9 rickshaws in a day?**

**Ans.** From one rickshaw she earns = Rs 20

From 2 rickshaws she will earn = Rs 20 x 2

From 3 rickshaws she will earn = Rs 20 x 3

Similarly from 9 rickshaws she will earn = Rs 20 x 9 = Rs 180

That is 9 times 20.

**2. For 10 rickshaws she will get Rs 20 x 10 = Rs 200.**

** So, for 9 rickshaws, she will get Rs 200 – _____ = ______**

**Ans**. For 9 rickshaws she will get Rs 200 – 20 = Rs 180.

**NCERT Textbook Page 63**

**1. Ina week how much does Kiran earn from one rickshaw?**

**Ans.** There are 7 days in a week.

In 1 day Kiran earns from one rickshaw = Rs 20

So, in 7 days Kiran will earn from one rickshaw = Rs 20 x 7 = Rs 140.

**2. Do it mentally and write the answers**

** 2 x 6 = ________ 4 x 80 = ________**

** 20 x 6 = ________ 4 x 81 = ________**

** 2 x 60 = ________ 9 x 25 = ________**

** 3 x 42 = ________ 31 x 9 = ________**

**Ans.**

2 x 6 = 12 4 x 80 = 320

20 x 6 = 120 4 x 81 = 324

2 x 60 = 120 9 x 25 = 225

3 x 42 = 126 31 x 9 = 279

**How Much to Pay for this Junk?**

**3. How much will Kiran pay for 31 kg newspaper?**

**Ans.** The cost of 1 kg of newspaper = Rs 5

So, the cost of 31 kg of newspaper = Rs 5 x 31

= Rs 155.

**NCERT Textbook Page 64**

**1. How much will Kiran pay for 42 kg newspaper?**

**Ans**. Kiran pays for 1 kg of newspaper = Rs 5

So, she will pay for 42 kg of newspaper = Rs 15 x 42

= Rs 210.

**2. Also find the cost of • 22 kg of plastic**

**Ans.** Rate of 1 kg of plastic = Rs 10

Therefore, cost of 22 kg of plastic = Rs 10 x 22

= Rs 220.

**• 23 kg of waste paper**

**Ans.** The cost of 1 kg of waste paper = Rs 4

Therefore, the cost of 23 kg of waste paper = Rs 4 x 23

= Rs 92.

**• 12 kg of iron**

**Ans**. The cost of 1 kg of iron = Rs 12

Therefore, the cost of 12 kg of iron = Rs 12 x 12

= Rs 144.

**3. Guess the total money Kiran will pay to the junk collectors. Will it be: — More than 600?**

** — Less than 600?**

**Ans.** The total money Kiran will pay to the junk collectors

The cost of 42 kg of newspaper = Rs 210

The cost of 22 kg of plastic = Rs 220

The cost of 23 kg of waste paper = Rs 92

The cost of 12 kg of iron = Rs 144

Total cost of all junks = Rs 666

Hence Kiran will pay more than Rs 600.

**NCERT Textbook Pages 64-66**

**Smart Kiran Sells the Junk**

**1. Kiran bought 1 kg plastic for Rs 10, but sold 1 kg plastic for Rs 12. How much**

** money does she earn on selling 1 kg plastic? Rs _______**

**Ans**. Kiran bought 1 kg plastic for Rs 10 and sold 1 kg plastic for Rs 12 So, she earn Rs 12 – Rs 10 = Rs 2.

**• So, how much money does she earn for 63 kg? Rs _______**

**Ans**. For 1 kg plastic she earns Rs 2.

Therefore, for 63 kg plastic she earns = Rs 2 x 63

= Rs 126

It can be calculated as follows:

You will get 126 by adding the digits in last row.

**B. Kiran sells 32 kg iron.**

**2. How much money will Dinu pay for 32 kg iron?**

**Ans.** 1 kg of plastic is sold in Rs 14

Therefore, 32 kg of plastic = Rs 14 x 32 = Rs 448 This can be calculated in similar manner

You can get the desired numbers by adding the numbers in bold

300 + 20 + 120 + 8 = 448

So, Dinu will pay Rs 448 for 32 kg of plastic.

**3. 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?**

**Ans**. Kiran earns by selling 1 kg of iron = Rs 14 – Rs 12

= Rs 2

So, she will earn by selling 32 kg of iron = Rs 2 x 32

= Rs 64

This can be calculated as follows also.

You will get the desired result by adding the numbers in last row

Which will be equal to 60 + 4 = 64

Hence, Kiran earns Rs 64 by selling 32 kg of iron.

**C. What will Dinu pay for 152 kg newspaper?**

**4. I bought 1 kg newspaper for Rs 5, but sold it for Rs 6. How much money did I earn by selling 152 kg of newspaper?**

**Ans.** She earn by selling 1 kg of newspaper

= Selling price of newspaper – Purchasing price of newspaper

=Rs 6-Rs 5 = Rs 1

Hence, she earned by selling 152 kg newspaper

= Rs 1 x 152 = Rs 152.

**D. What does Dinu pay for brass?**

**5. How much money will Dinu pay for 4 kg brass?**

**Ans.** The rate of 1 kg of brass according to Dinu’s price list = Rs 180

So, Dinu will pay for 4 kg of brass = Rs 180 x 4

= Rs 720

This can be calculated as follows:

By adding the digits in last row you will get 400 + 320 = 720 Hence, Dinu will pay Rs 720 for 4 kg of brass.

**NCERT Textbook Page 67**

**1. First, guess the answer and then calculate**

** (a) 37 x 18 = (b) 45 x 24 = (c) 69 x 52 =**

** (e) 142 x 5 = (f) 382 x 3 = (g) 2 x 175 =**

** (d) 77 x 55 = (ft)4 x 206 =**

**Ans.**

(a) Guess = 37 x 18 means 40 x 20 = about 800

**Calculation**

By adding the digits in third and fifth rows you will get

300 + 70 + 240 + 56 = 666

Hence, 37 x 18 = 666.

(b) Guess 45 x 24

Then will be near to 40 x 25 = 1000

**By Calculation**

By adding the numbers in third and fifth rows you will get

800 + 100 + 160 + 20 = 1080

So, 45 x 24 = 1080.

(c) On guessing 69 x 52, the numbers will be near to 70 x 50 = 3500

**Calculation**

By adding the numbers in third and fifth rows you will get

3000 + 450 + 120 + 18 = 3588

So, 69 x 52 = 3588.

(d) On guessing 77 x 55

The numbers will be near to 80 x 50 = 4000

**Calculation:**

By adding the numbers in third and fifth rows you will get

3500 + 350 + 350 + 35 = 4235

Hence, 77 x 55 = 4235.

(e) On guessing 142 x 5

The number will be near to 140 x 5 = 700

**On calculation**

By adding the numbers in last row you will get

500 + 200 + 10 = 710 .

Hence, 142 x 5 = 710.

(f) 382 x 3

On guessing this number will be near to 380 x 3 = 1140

**On calculation:**

By adding the numbers in last row you will get

900 + 240 + 6 = 1146

So,-382 x 3 = 1146.

(g) 2 x 175

This number will be near to 2 x 175 = 350

**On calculation:**

By adding numbers in last row you will get

200 + 140 + 10 = 350.

(h) 4 x 206

This number will be near to 5 x 200 = 1000

**On calculation:**

By adding the numbers in last row you will get

800 + 24 = 824

So, 4 x 206 = 824.

**NCERT Textbook Page 68**

**Fill My Diary**

**1. Now you make a record in her diary.**

Find out how much she earned this time.