Chapter 6: The Junk Seller

Answer: For 1 kg newspaper Kiran pays = Rs 5

For 42 kg of newspaper, she will pay = Rs 5 × 42

= Rs 210

Hence, Kiran pays Rs 210 for 42 kg of newspaper.

(a) The cost of 1 kg of plastic = Rs 10

So, the cost of 22 kg of plastic will be = Rs 10 × 22

= Rs 220

(b) Rate of 1 kg of waste paper = Rs 4

Hence, the cost of 23 kg of waste paper = Rs 4 × 23

= Rs 92

(c) The cost of 1 kg of iron = Rs 12

Hence, the cost of 12 kg of iron will be = Rs 12 × 12

= Rs 144

Answer: Total money Kiran pays to the junk collectors are

Cost of 42 kg of newspaper = Rs 210

Cost of 22 kg of plastic = Rs 220

Cost of 23 kg of waste paper = Rs 92

Cost of 12 kg of iron = Rs 144

Therefore, the total cost of all the junk = Rs 666

So, Kiran pays more than Rs 600.

NCERT book Page No: 64-66

Smart Kiran Sells the Junk

Answer: The cost of 1 kg of plastic that Kiran bought = Rs 10

She sold 1 kg of plastic for Rs 12.

Hence, she earned = Rs 12 – Rs 10

= Rs 2

Answer: She earns Rs 2 for 1 kg of plastic.

For 63 kg of plastic, she earns = Rs 2 × 63

= Rs 126

Therefore, Kiran earns Rs 126 for 63 kg of plastic.

This can be calculated as follows:

By adding the digits in the last row, we will get 126.

Kiran sells 32 kg iron

Answer: The amount by which 1 kg of plastic is sold = Rs 14

Hence, the cost of 32 kg of plastic = Rs 14 × 32

= Rs 448

This can be calculated as follows:

By adding the bold numbers, we get the desired number.

300 + 20 + 120 + 8 = 448

Hence, the money paid by Dinu for 32 kg of plastic is Rs 448.

Answer: Money earned by Kiran by selling 1 kg of iron = Rs 14 – Rs 12

= Rs 2

Hence, money earned by her by selling 32 kg of iron = Rs 2 × 32

= Rs 64

This can be calculated as follows:

By adding the numbers in the last row, we can find the desired number.

60 + 4 = 64

Therefore, by selling 32 kg of iron, Kiran earn Rs 64.

What will Dinu pay for 152 kg newspaper?

Answer: Money earned by selling 1 kg of newspaper = Selling price of newspaper – Purchasing price of newspaper

= Rs 6 – Rs 5

= Rs 1

Money earned by her by selling 152 kg of newspaper = Rs 1 × 152

= Rs 152

Therefore, she earns Rs 152 by selling 152 kg of newspaper.

What does Dinu pay for brass?

Answer: As per Dinu’s price list, the cost of 1 kg of brass = Rs 180

For 4 kg of brass, Dinu will pay = Rs 180 × 4

= Rs 720

This can also be calculated as follows:

We get the desired result by adding the digits in the last row.

400 + 320 = 720

Hence, for 4 kg brass Dinu pays Rs 720.

NCERT book Page No: 67

(a) Here, the number will be near 40 × 20, i.e., about 800.

Calculation:

Now, add the digits in the third and fifth rows, and we get

300 + 70 + 240 + 56 = 666

Therefore, 37 × 18 = 666

(b) 45 × 24

This number will be near 40 × 25 = 1000

Calculation:

Add the digits in the third and fifth rows, and we get

800 + 100 + 160 + 20 = 1080

Hence, 45 × 24 = 1080

(c) 69 × 52

Here, the number will be near 70 × 50 = 3500

Calculation:

On adding the digits in the third and fifth rows, we get

3000 + 450 + 120 + 18 = 3588

Hence, 69 × 52 = 3588

(d) By guessing 77 × 55

The number will be near 80 × 50 = 4000

Calculation:

On adding the numbers in the third and fifth rows, we get

3500 + 350 + 350 + 35 = 4235

Therefore, 77 × 35 = 4235

(e) On guessing 142 × 5

The number will be near 140 × 5 = 700

Calculation:

By adding the numbers in the last row, we get

500 + 200 + 10 = 710

Therefore, 142 × 5 = 710

(f) 382 × 3

The number will be near 380 × 3 = 1140 on guessing.

Calculation:

On adding the digits in the last row, we will get

900 + 240 + 6 = 1146

So, 382 × 3 = 1146

(g) 2 × 175

On guessing this number will be near 2 × 175 = 350

Calculation:

On adding the digits in the last row, we get

200 + 140 + 10 = 350

(h) 4 × 206

This number will be near 5 × 200 = 1000 on guessing.

Calculation:

On adding the digits in the last row, we get

800 + 24 = 824

Therefore, 4 × 206 = 824

Fill My Diary

Later, she paid Rs 919 to the junk collectors. When she sold the junk, she got these notes and coins from Dinu.