**NCERT Solutions for Class 4 Mathematics**** ****Math Magic for**** Chapter 6 The Junk Seller**

**Chapter -6**

**THE JUNK SELLER**

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

**Ans.**I do not find Maths difficult.

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

**Ans.**The chapter entitled “The Way the World Looks” is the most difficult thing in Maths book.

3. What do you think is the easiest lesson?

**Ans.**The lesson “A Trip to Bhopal” is the essential.

4. Find out: how much for a cup of tea?

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

**(a) At a tea stall**

**Ans. (a)**At a tea stall, the cost of a cup is Rs 3.

**(b) At a hotel**

**Ans. (b)**At a hotel, the cost of a cup is Rs 10.

5. If a person who runs a tea stalls earns Rs 30 in a day, how much will he earn in 10 days? And in a month? How did you get the answer? Discuss.

**Ans.**Earning of a tea stall owner per day = Rs 30

Therefore, earning of a tea stall owner in 10 days = Rs (10 30) = Rs 300

And his, earning in a month = Rs (30 30) = Rs 900

I got the answers by multiplication.

6. Find out: What is a loan?

**(a) Have you ever heard of someone taking a loan? For what?**

**Ans. (a)**Yes, I have heard of someone taking a loan. It is taken to buy a handcart.

**(b) How much loan was taken?**

**Ans. (b)**Rs 300 was taken as loan.

**(c) How much money was paid back.**

**Hariya and Babu went to buy a handcart for Rs 300.**

**Ans. (c) Hariya:**I have taken a loan of Rs 300 from a Bank for six months. I will pay Rs 51 every month to the bank.

**Babu:**But I have taken a loan of Rs 300 from Chunnilal. After six months, I will pay back Rs 360.

**(d) Who has to pay back more- Hariya or Babu?**

**Ans. (d)**In case of Hariya: Money paid back to the bank = Rs. 6 51 = Rs 306

In case of Babu: Money paid back to Chunnilal = Rs 360

Since, Rs 360 is more than Rs 300, therefore, Babu paid back more money.

7. (a) Have 9 rickshaws of my own. I give the rickshaws on rent, each of Rs 20 a day. On Sundays I do not take any money from them? How much does Kiran earn from 9 Rickshaws in a Day?

**Ans. (a)**For 1 rickshaw she gets Rs 20 per day.

So, for 9 rickshaws she will earn Rs 180.

**(b) How did you do it?**

**Ans. (b)**I did it by multiplying 20 and 9 (20 9=180).

8. In a week how much does Kiran earn from one rickshaw?

**Ans.**Since on Sundays Kiran does not take any money for rickshaw’s rent, therefore, Kiran earns in a week on one rickshaw at the rate of Rs 20 per day = Rs 6 20 = Rs 120.

9. Do it mentally and write the answers:

**(a) 2 6= __**

**Ans. (a)**2 6= 12.

**(b) 20 6 = __**

**Ans. (b)**20 6 = 120.

**(c) 2 60 = __**

**Ans. (c)**2 60 = 120.

**(d) 3 42 = __**

**Ans. (d)**3 42 = 126.

**(e) 4 80 = __**

**Ans. (e)**4 80 = 320.

**(f) 4 81 = __**

**Ans. (f)**4 81 = 324.

**(g) 9 25 = __**

**Ans. (g)**9 25 = 225.

**(h) 31 9 = __**

**Ans. (h)**31 9 = 279.

10. 4 81 is 4 more than 4 80. Am I right?

**Ans.**Yes.

11. How much Kiran will pay for 31 kg newspaper?

**Ans.**Kiran will pay for 31 kg newspaper = Rs (51 30 + 5 1) = Rs 155.

12.

**(a) How much Kiran pay for 42 kg newspaper?**

**Ans. (a)**Kiran will pay Rs (42 5) = Rs 210.

**(b) Also find the costs of:**

**(i) 22 kg of plastic**

**Ans. (b) (i)**Cost of 22 kg of plastic = Rs (22 10) = Rs 220.

**(ii) 23 kg of wastepaper**

**Ans. (b) (ii)**Cost of 23 kg of newspaper = Rs (23 4) = Rs 92.

**(iii) 12 kg of iron.**

**Ans. (b) (iii)**Cost of 12 kg of iron = Rs (12 12) = Rs 144.

13. Can you do this without writing? Guess the total money Kiran will pay to the junk collectors. Will it be: More than 600? Less than 600?

**Ans.**Less than 600.

14. Kiran bought 1 kg of plastic for Rs 10, but sold 1 kg plastic for Rs 12. How much money does she earn on selling 1 kg plastic?

**Ans.**Earning on selling 1 kg of plastic = Selling price – Cost price = Rs 12 – Rs 10 = Rs 2

So, earning on selling 63 kg of plastic = Rs 2 Rs 63

60 | 3 |

60 2 | 3 2 |

120 | 6 |

On adding the numbers in the last row = 120 + 6 = 126.

So, for 63 kg of plastic, Kiran earns = Rs 126.

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

**Ans.**The rate of 1 kg of iron is Rs 14. So, the cost for 32kg of iron is Rs 14 32.

We write as:

30 | 2 | |

10 | 30 10 | 2 10 |

300 | 20 | |

4 | 30 4 | 2 4 |

120 | 8 |

So, for 32 kg iron, Dinu will pay Rs 448.

16. 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.**Earning of selling 1 kg iron = Selling price -Cost price = Rs 14 – Rs 12 = Rs 2

So, earning on selling 32 kg of iron = Rs 2 32 of iron = Rs 2 32

We write as:

30 | 2 |

30 2 | 2 2 |

60 | 4 |

So, Kiran earns Rs 64 on the sale of 32 kg iron.

17. 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.**Rs 152.

18. How much money will Dinue pay for 4 kg brass? Guess the answer first.

**Ans.**The rate of 1 kg brass is Rs 170. So, the cost of 4 kg brass is Rs 170 4. We guess the answer to lie between Rs 600 and Rs 800.

We write as:

4 | 100 | 70 |

100 4 | 70 4 | |

400 | 280 |

So, for 4 kg brass Dinu will pay Kiran Rs 680.

19. First guess the answer then calculate:

**(a) 37 18**

**Ans. (a)**On guessing 37 18 may be = 740.

We write as:

30 | 7 | |

10 | 30 10 | 7 10 |

300 | 70 | |

8 | 30 8 | 7 8 |

240 | 56 |

Adding the numbers = 300 + 240 + 70 + 56 = 666

So, 37 18 = 666.

**(b) 45 24**

**Ans. (b)**On guessing 45 24 = 1080

We write as:

40 | 7 | |

20 | 40 20 | 5 20 |

800 | 100 | |

4 | 40 4 | 5 4 |

160 | 20 |

Adding the numbers = 800 + 160 + 100 + 20 = 1080

So, 45 24 = 1080

**(c) 69 52**

**Ans. (c)**On guessing 69 52 = 3588

We write as:

60 | 9 | |

50 | 60 50 | 9 50 |

3000 | 450 | |

2 | 60 2 | 9 2 |

120 | 18 |

Adding the numbers = 3000 + 120 + 450 + 18 = 3588

So, 69 52 = 3588.

**(d) 77 55**

**Ans. (d)**On guessing 77 55 = 4235

We write as:

70 | 7 | |

50 | 70 50 | 7 50 |

3500 | 350 | |

5 | 70 5 | 7 5 |

350 | 35 |

Adding the numbers = 3500 + 350 + 350 + 35 = 4235

So, 77 55 = 4235.

**(e) 142 5**

**Ans. (e)**On guessing 142 5 = 710

We write as:

100 | 40 | 2 | |

5 | 100 5 | 40 5 | 2 5 |

500 | 200 | 10 |

Adding the numbers = 500 + 200 + 10 = 710

So, 142 5= 710.

**(f) 382 3**

**Ans. (f)**On guessing 382 3 =1146

We write as:

300 | 80 | 2 | |

3 | 300 3 | 80 3 | 2 3 |

900 | 240 | 6 |

Adding the numbers = 900 + 240 + 6 = 1146

So, 382 3 = 1146

**(g) 2 175**

**Ans. (g)**On guessing 2 175 = 350

We write as:

100 | 70 | 5 | |

2 | 100 2 | 70 2 | 5 2 |

200 | 140 | 10 |

Adding the numbers = 200 + 140 + 10 = 350

So, 2 175 = 350.

**(h)****4 206**

**Ans. (h)**On guessing 4 206 = 824

We write as:

200 | 0 | 6 | |

4 | 200 4 | 0 4 | 6 4 |

800 | 0 | 24 |

Adding the numbers = 800 + 0 + 24 = 824

So, 4 206 = 824.

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