Ways to Multiply and Divide

Questions with the (*) sign are open ended questions.

Page 170

Maniratnam – the cashier

Maniratnam wanted to calculate the salary of the cook for the month of January. He wrote –

Rupees 1800 + 150 + 60 + 5 = Rs 2015

Maniratnam’s daughter Bela has learnt another method to multiply. She wrote like this and showed it to Bhanu, her brother.

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Now Bhanu tried to find the salary of a minister for the month of January. He wanted to multiply 195 X 31.

Practice Time

1) Use Bela’s method to multiply these numbers.

a) 32 X 46

b) 67 X 18

2) Do these in your notebook using Bela’s method.

a) 47 X 19 b). 188 X 91

c) 63 X 57 d). 225 X 22

e) 360 X 12 f). 163 X 42

page 172

Shantaram a Special Cook.

Shantaram is a special cook who comes only on party days. Last year he was called only for 28 days. For each day he has to be paid Rs 165. Find out how much money he will get in all.

Ans: Shantaram will get ₹ 3620 in all.

If he called for all days of the year, how much salary he will get?

Ans: Shantaram will get ₹ 60225.

Now find the salaries of the minister and horse rider for 1 year.

Ans: The salary of the minister for 1 year is ₹ 71175.

The salary of the horse-rider for 1 year is ₹ 27740.

Years and Years

a) Soham drinks 8 glasses of water every day. How many glasses will he drink in one month?

Number of days in one month = 30

30 X 8 = 240

Ans: Soham will drink 240 glasses in one month

How many glasses will he drink in one year?

Number of days in one year = 365

365 X 8 = 2920

Ans: Soham will drink 2920 glasses in one year.

If 125 people living in a colony drink 8 glasses of water in a day, how much water will they drink in a year?

Ans: People in colony will drink 365000 glasses in one year.

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b) If Soha’s heart beats 72 times in one minute, how many times do it beat in one hour?

Ans: Soha’s heart beat 4320 times in one hour.

Now find out how many times it beat in one day.

Ans: Soha’s heart beat 103680 times in one day.

Count your own heart beats to find out how many times your heart beats in one week.

Ans: My heart 725760 times in one week.

c) A baby elephant drinks around 12 L of milk every day. How much milk will it drink in two years?

Ans: Baby elephant will drink 8760 L of milk in two years.

d) A baby blue whale drinks around 200L of milk in one day. Just imagine how much milk that is! Find out in how many days you family would use 200 L milk. How much milk would the baby blue whale drink in eight months?

Ans: My family needs 1 L of milk everyday. So, we need 200 days to use 200L milk.

Baby blue whale drink 45000L in eight months.

Page 174

Karunya – The Landlord

Karunya has three fields, Field(A), Field(B) and Field(C). Find the area of all the three fields.

Field(A) = 756 square meters.

Field(B) = 432 square meters.

Field(C) = 513 square meters.

He bought field(A) at the rate of Rs 95 for a square metre, field(B) at Rs 110 for a square metre and field(C) at Rs 120 for a square metre. Find the cost of all three fields.

The cost of field A is ₹ 71820

The cost of field B is ₹ 47520

The cost of field C is ₹ 61560

Thulasi and her husband work in Karunya’s farm. The Government has said that farm workers should be paid at least Rs 71 for one day’s work. But he pays Rs 55 to Thulasi and Rs 58 to her husband.

If Thulasi works for 49 days, how much money does she get?

Ans: Thulasi will get ₹ 2695

If her husband works for 42 days, how much money does he get?

Ans: Thulasi’s husband will get ₹ 2436

Find the money they earn together.

Ans: Together they earn ₹ 5131

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The table shows the amounts fixed by four states.

a) For farm work which state has fixed the highest amount? Which state has fixed the lowest?

Ans: Haryana state has fixed the highest amount and Rajasthan state has the lowest.

b) Bhairon Singh is a worker in Rajasthan. If he works for 8 weeks on the farm, how much he will earn?

Ans: Bhairon Singh will earn ₹ 4088.

c) Neelam is a worker in Haryana. If she works for 2 ½ months on the farm, how much she will earn?

2 ½ months means 2 X 30 + 15 = 75 days

Neelam will earn ₹ 10125

d) How much more will a farm worker in Madhya Pradesh get that a worker in Orissa after working for 9 weeks?

Ans: Farm worker in Madhya Pradesh will earn more.

Page 176

Satish’s Story

Satish is a 13-year-old boy. His father had taken a loan for farming. But the crops failed. Now Satish’s mother has to pay Rs 5000 every month for the loan.

Satish started working – he looked after 17 goats of the village. He earns Rupee 1 every day for one goat. How much will he earn in one month?

Total number of goats = 17

Earning for one day = 17 X 1 = 17

Earning for one month = 30 X 17 = ₹ 510

Does he earn enough to help pay the loan every month?

No, he does not earn enough to help to pay the loan.

How much will he earn in one year?

Satish earn 510 per one month

Number of months in a year = 12

Satish earn ₹ 6120 in one year.

Kamla Bai’s Story

To help farmers the State Government gave cows. Kamla Bai Gudhe also got a cow. The cost of the cow was Rs 17,500. She had to pay Rs 5,500 and the government spent the rest of the money.

How much did the government spend on the cow?

Cost of the cow = ₹ 17500

Kamla Bai paid = ₹ 5500

Amount paid by the government = 17500 – 5500

= ₹ 12000

If 9 people from her village got cows, how much did the government spend in all?

Government spend = 12000 X 9

= 108000

If Kamla Bai spends Rs 85 a day, find out how much she will spend in one month.

Ans: Kamla Bai will spend ₹ 2550 in one month

The cow gives 8 litres of milk everyday. How much will it give in one month?

Ans: the cow will give 240 litres of milk in one month

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If the milk is sold at Rs 9 per litre, how much money will Kamla Bai make in one month?

Money earned by Kamla Bai = 240 X 9

=₹ 2160

So the money spent on keeping the cow was Rs 2550

Money earned by selling the milk Rs 2160

Which is more — money spent on the cow or money earned from it? How much?

2550 – 2160 = 390

Money spent on the cow is more than money earned from it by

₹ 390

Explain why she wanted to sell the cow.

Money earned is less than money spent on the cow. Therefore, she wanted to sell the cow.

Practice time

a) Sukhi works on a farm. He is paid Rs 98 for one day. If he works for 52 days, how much will he earn?

Ans: Sukhi earns ₹ 5096

b) Hariya took a loan to build his house. He has to pay back Rs 2,750 every month for two years. How much will he pay back in 2 years?

Ans: Hariya pay back ₹ 66000 in two years.

c) Ratiram is a milk seller in the city. He sells 13 litres of milk everyday at Rs 23 per litre. How much does he earn?

Ans: Ratiram earn ₹ 299 per day

d) A farmer sells 1 litre of milk for Rs 11. In one month he sells 210 litres of milk. How much does he earn in a month?

Ans: The farmer earns ₹ 2310 in a month.

e) A company sells 1 litre of packed water for Rs 12. A shopkeeper buys 240 litres of packed water. How much does he pay?

Ans: The shop keeper has to pay ₹ 2880.

Page 178

Fun with Multiplication

A) look for the pattern and take this forward.

(0 X 9) + 1 = 1

(1 X 9) + 2 = 11

(12 X 9) + 3 = 111

(123 X 9) + 4 = ______

(1234 X 9) + 5 = _______

(12345 X 9) + 6 = _______

Answer:

(0 X 9) + 1 = 1

(1 X 9) + 2 = 11

(12 X 9) + 3 = 111

(123 X 9) + 4 = 1111

(1234 X 9) + 5 = 11111

(12345 X 9) + 6 = 111111

B) Each letter a b, c here stands for a number.

Ans: b= 2 c= 3

C) Trick with your age.

Write your age

Multiply it by 7

Again multiply the answer by 13

Multiply again that answer by 11

Now look at your answer. Can you find your age in that answer? How many times does your age show in the answer?

Now try this trick with other people.

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D) going round and round

Do you find a pattern in all these answers? Discuss this with your friends?

Division

Dolma took a loan from a friend to buy a moped for Rs 9,588. She has to pay it back in equal amounts every month for six months.How much will she have to pay every month? She asked her children to calculate.

Her daughter did it this way

Her son started this way. Now you complete it.

Will both of them get the same answer? Discuss.

Yes both of them get the same answer.

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Practice Time

Try to solve these using as few steps as you can.

a) 4228 ÷ 4 b) 770 ÷ 22

c) 9872 ÷ 8 d) 672 ÷ 21

e) 772 ÷ 7 f) 639 ÷ 13

How Many Times?

976 children are going on a picnic. They will be taken in mini buses. If 25 children can go in one bus, how many buses do they need?

Two children have solved it.

Check if they have made a mistake—correct it. Discuss.

Page 181

How Much Petrol?

Isha has Rs 1000 with her. She wants to buy petrol. One litre of petrol costs Rs 47. How many litres can she buy?

Money with Isha = Rs 1000

Cost of 1litre = Rs 47

Litres of petrol she can buy = Rs 1000 ÷ Rs 47 = ?

Isha can buy 21 litres of petrol.

If Isha comes to your city, how much petrol can she buy with the

same money?

Do it yourself.

Children’s Day

Children are happy today. They are celebrating Children s Day.

Each child will be given 4 coloured pencils from school. The school has got 969 pencils. To find out how many children can get pencils the teacher asks them to divide.

Iru’s Way Sreeni’s Way

Complete Iru’s and Sreeni’s way of division. What is the answer

you get?

Ans: The answer is 242.

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Shivangi did it buy a shortcut way.

Page 183

Practice Time

576 books are to be packed in boxes. If one box has 24 books, how many boxes are needed?

Ans: 24 boxes are needed.

836 people are watching a movie in a hall. If the hall has 44 rows, how many people can sit in 1 row?

Ans: 19 people can sit in 1 row.

A gardener bought 458 apple trees. He wants to plant 15 trees in each row. How many rows can he plant?

Ans: 30 rows he can plant.

How many trees would be left over?

Ans: 8 trees would be left.

Brain Teaser

Shyamli bought a battery. She read on it Life: 2000 hours . She uses it throughout the day and the night. How many days will the battery run?

Ans: It will run for 83 days.

More with Multiplication and Division

A tank is full of 300 L of water. How much water will be filled in 25 tanks? If 15 buckets can be filled with one tank of water, how many buckets in all can be filled with the water in 25 tanks?

The water filled in 25 tanks is 7500 L

Total buckets can be filled are 112500

There are 28 laddoos in 1 kg. How many laddoos will be there in 12 kg? If 16 laddoos can be packed in 1 box, how many boxes are needed to pack all these laddoos?