Page 1 :
Class 5 Maths Chapter 13, Ways To Multiply And Divide, Page 170, Maniratnam—The Cashier, Maniratnam is the cashier of king Jayan. His job is to find out the salary of all, the people who work for the king. This chart shows how much salary each, person gets in a day., , Maniratnam wanted to calculate the salary of the cook for the month of, January. He wrote:, , Rupees 1800 + 150 + 60 + 5 = Rs2015, Maniratnam’s daughter Bela had learnt another method to multiply. She wrote, like this and showed it to Bhanu, her brother., Akka, how did you do this?, , You can multiply 65 with 31 in two steps. You know that 31 is 30 + 1. So, in, the, first step multiply 65 with 1 and in the second step multiply 65 with 30., Now Bhanu tried to find the salary of a minister for the month of January. He, wanted to multiply 195 x 31
Page 2 :
First step: Multiply 195 by 1, Second step: Multiply 195 by 30, Page 171, Practice Time, 1.Use Bela’s method to multiply these numbers., Ans., , 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, Ans., , Page 172, Shantaram—A Special Cook, 1. Shantaram is a special cook who comes only on party days. Last year he, was
Page 3 :
called for only 28 days. For each day he has to be paid ? 165. Find out how, much, money he will get in all., Ans.Wages for a day = Rs 165, Number of days worked = 28, , Shantaram got Rs 4620, 2.If he is called for all days of the year, how much salary will he get?, Ans., , Rs 60225., 3. Now find the salaries of the minister and horse rider for 1 year., Ans. Minister’s salary for one day = Rs 195, , Rs 71,175.
Page 4 :
Horse rider’s salary for one day = Rs76, , Rs 27,720, Years and Years, (а) Sohan drinks 8 glasses of water everyday., 1.How many glasses will he drink in one month?, Ans.8 x 30 = 240, 2.How many glasses will he drink in one year?, Ans.8 x 365 = 2920, 3.If 25 people living in a colony drink 8 glasses of water in a day, how much, water –, will they drink in a year?, Ans.8 x 125 = 1000, They will drink 1000 glassed of water in a day, Hence, in 365 days they will drink:, 365 x 1000 = 365,000 glasses of water, 4.Can you guess how many glasses of drinking water are used in a day in, your colony?, Ans.Number of people in my colony = 500 Hence, 8 x 500 = 4000, Page 173, (b)If Soha’s heart beats 72 times in one minute, how many times does it beat, in one hour?, •Now find out how many times it beats in one day., •Count your own heart beats to find out how many times your heart beats in, one week., Ans.Number of heart beats in 1 minute = 72, Hence,number of heart beats in 1 hour or 60 minutes = 60 x 72 = 4320, Number of heart beats in 1 day or 24 hours = 4320 x 24 = 103680
Page 5 :
My heart beats 70 times in a minute., Hence, my heart beats in 1 hour = 70 x 60 = 4200, My heart beats in 1 day = 4200 x 24 = 100800, My heart beats in 1 week = 104800 x 7 = 705600, (c)A baby elephant drinks around 12 L of milk every day. How much milk will it, drink in two years?, Ans.Number of days in 2 years = 365 x 2 = 730, Milk consumed in 1 day = 12 L, Hence, milk consumed in 730 days = 730 x 12 = 8760 L, , Hence, the baby elephant consumes 8,760 L of milk in two years., (d)A baby blue whale drinks around 200 L of milk in one day. Just imagine, how much milk that is! Find out how many days your family would use 200 L, milk. How much milk would the baby blue whale drink in eight months., Ans. Milk consumed by baby whale in 1 day = 200 L, Milk consumed by baby whale in 30 days = 200 x 30 = 6000 L Milk consumed, by baby whale in 8 months = 6000 x 8 = 48000 L My family consumes 5 L, milk in a day, Hence, number of days for consuming 200 L milk = 200÷5=40 days, Page 173, Karunya—The Landlord, Karunya bought three fields, , 1.Find the area of all the three fields., Field (A)………………square metre
Page 6 :
Field (B)………………square metre, Field (C)………………square metre, Ans., , 2.He bought field (A) at the rate of Rs95 for a square metre, field (B) at Rs110, for a square metre and field (C) at Rs 120 for a square metre. Find the cost of, all three fields, Ans.
Page 7 :
Now, cost of all three fields, = 71820 + 47520 + 61560 = Rs 1,80,900, 3.Thulasi and her husband work on Karunya’s farm. The Government has, said, that farmworkers should be paid at least Rs 71 for one day’s work. But he, pays, Rs 55 to Thulasi and Rs58 to her husband., •If Thulasi works for 49 days, how much money does she get?, •If her husband works for 42 days, how much money does he get?, •Find the money they earn together., Ans. Thulasi’s one day’s wages = Rs 55, Hence, 49 day’s wages = 49 x 55 = Rs 2695, , Her husband’s one day’s wages = Rs 58, Hence, 42 day’s wages = 58 x 42 = Rs 2436
Page 8 :
Their combined earnings 2695 + 2436 = Rs 5131, Page 175
Page 9 :
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 ? 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?, Does he earn enough to help pay the loan every month?, How much will he earn in one year?, Ans., , 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 Rs17500. She had to pay Rs 5500 and the, government spent the rest of the money., 1.How much did the government spend on the cow?
Page 10 :
Ans. Cost of the cow = Rs17500, Money paid by Kamla Bai = Rs5500 \Hence, money spent by the government = 17500 — 5500 =Rs 12000, 2.If 9 people from her village got cows, how much did the government spend, in all?, Ans.Government spends Rs12000 for one cow Hence, for 9 cows the, government spends 12000 x 9 = Rs 108000.But Kamla Bai was not happy., She had to spend Rs 85 every day on the cow. She made some money by, selling the milk. But still she wanted to sell the cow., 3.If Kamla Bai spends Rs85 a day, find out how much she will spend in one, month., Ans.Money spent in one day = Rs85 Hence, money spent in one month = 85, x 30 = Rs 2550, 4.The cow gives 8 litres of milk every day. How much will it give in one month?, Ans.Milk in 1 day – 8 litre Milk in one month = 8 x 30 = 240 L, 5.If the milk is sold at Rs 9 per litre, how much money will Kamla Bai make in, one month?, Ans. Price of one litre milk = Rs 9, Hence, price of 240 L milk = 9 x 240 = Rs 2160, •So, the money spent on keeping the cow was ?, Ans. Rs 2550, •Money earned by selling the milk ?, Ans. Rs 2160, •Which is more money spent on the cow or money earned from it?, How much?, Ans. The money spent on cow is more than the money earned from it., Difference = 2550 – 2160 = Rs390, 6.Explain why she wanted to sell the cow., Ans. She is running into losses. Hence, she wants to sell the cow., Page 177, 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.
Page 11 :
(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. Amount of loan that is to be paid every month = Rs2750 Hence, loan to, be paid in a year = 2750 x 12 = Rs 33000 Loan to be paid in 2 years =, 33000×2 = Rs 66000, (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?
Page 12 :
Ans., , 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 = 1111, (1234 x 9)+5 = 11111, (12345 x 9)+6 = 111111, Ans. Number of 1 increases at every step in this pattern, (B) Each letter a, b, c here stands for a number, , Take a = 1, then find what the numbers b and c will be., Ans.If a=1, then we have, , Hence, b=2andc = 3, (C) Tricks with your age Write your age:, 10 years Multiply it by 7:, 7×10 = 70, Again multiply the answer by 13:, 70×13 = 910
Page 13 :
Multiply again that answer by 11:, 910 x 11 = 10010, 1.Now look at your last answer. Can you find your age in that answer?, Ans. Yes, my age ‘10’ occurs twice in the last answer., 2.Now try this trick with other people., Ans.Let us take age = 9 years, Multiply by 7:, 9 x 7 = 63, Multiply by 13:, 63 x 13 = 819, Multiply by 11:, 819 x 11 = 9009, The age ‘9’ occurs twice in the last answer., (D)Going round and round!, 142857 x 1 = 142857, 142857 x 2 = 285714, 142857 x 3 =428571, 142857 x 4 = 571428, 142857 x 5 = 714285, Do you find a pattern in all these answers? Discuss this with your friends., Ans. Yes, we have some pattern each time take starting point 1 more than the, previous, i.e. 1, 2, 4, 5, 7, etc.If we move clockwise we get the answer:, Page 179, Division, Dolma took a loan from a friend to buy a moped for ? 9588. She has to pay it, back in equal amounts every month for six months., 1.How much will she have to pay every month? She asked her children to
Page 14 :
calculate. Her daughter did it this way
Page 15 :
Ans., , Page 180, Practice Time, Try to solve these using as few steps as you can, (a) 4228 + 4
Page 16 :
Ans.
Page 17 :
(d) 672, , 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?, 1.Two children have solved it. Check if they have made a mistake, correct it., Discuss
Page 18 :
Ans. In the first solution, the mistake is in remainder. The remainder should be, 1 instead of zero., In the second solution; the error is in third and fourth steps of division. The, quotients in those steps should be 5 and 4 as shown below:, , If one extra child can be accommodated in one of the buses then we need 39, buses., Otherwise we need 40 buses. Since, taking 1 bus for 1 child is not possible so, 39 buses will do., Page 181, How Much Petrol?, 1.Isha has Rs1000 with her. She wants to buy petrol. One litre of petrol costs, Rs47. How many litres can she buy
Page 19 :
Find Out, 1.If Isha comes to your city, how much petrol can she buy with the same, money? Ans. At present the cost of petrol is 168 per litre in my city., , Page 181, 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., Ira’s way
Page 20 :
1.Complete Iru’s and Sreeni’s way of division., , Page 183, Practice Time, 1.576 books are to be packed in boxes. If one box has 24 books, how many, boxes’ are needed?
Page 21 :
Ans., , 2.836 people are watching a movie in a hall. If the halt has 44 rows, how, many people can sit in one row?, Ans, , 3.A gardener bought 458 apple trees. He wants to plant 15 trees in each row., How many rows can he plant?, How many trees would be left over?, Ans.
Page 22 :
Brain Teaser, 4. 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., , More with Multiplication and Division, 1.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?, Ans. Water in 1 tank = 300 L, So, water in 25 tanks = 300 x 25 = 7500 L, Now, Water in 1 tank = 15 buckets, So, water in 25 tanks = 25 x 15 = 375 buckets, 2.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?, Ans. Number of laddoos in 1 kg = 28, Hence, number of laddoos in 12 kg = 28 x 12 = 336 laddoos Number of, laddoos in 1 box =16 Total number of laddoos = 336, Hence, number of boxes needed for 336 laddoos = 336 + 16 = 21 20 + 1 16), 336 -320 16 -16 X, 3.There are 26 rooms in a school. Each room has 4 plants. If each plant, needs 2 cups of water, how much water do we need for all plants?, Ans. Water needed for 4 plants = 4×2 = 8 cups, Water needed for 26 rooms = 26 x 8 = 208 cups, Page 184
Page 23 :
Make the Best Story Problem, Each line gives a story. You have to choose the question which makes the, best story problem. The first one is already marked., 1.A shopkeeper has 50 boxes. There are 48 fruits in one box., Tick the one question which matches with the given problem., (a) How much will the shopkeeper pay in all?, (b) How many fruits are there in all?, (c) How many more boxes will he need?, Ans. (6) is the best choice, Option (a) is not a good choice because price is not given in the story, Option (c) is not a good choice because total number of boxes is given in the, story., 2.352 children from a school went on a camping trip. Each tent had a group of, 4 children., (a) How many children did each tent have?, (b) How many tents do they need?, (c) How many children in all are in the school?, Ans. (b) is the best choice, Option (a) is not a good choice because number of children for each tent is, already given., Option (c) is not a good choice because total number of children is already, given., 3.A shopkeeper has 204 eggs. He puts them in egg trays. Each tray has 12, eggs., (а) How many more eggs will he needed?, (б) How many fresh eggs does he sell?, (c) How many egg trays does he need?, Ans. (c) is the best choice., Option (a) is not a good choice because total number of eggs is already given., Option (b) is not a good choice because there is no data on number of fresh, or spoiled eggs. ., 4.The cost of one book is Rs47. Sonu buys 23 books., (а) How much moneybooks?, Ans. (b) is the best choice, Page 186, Practice Time, 1.Do these divisions. Check your results by multiplication., (a)438, Quotient = 48 and remainder = 6, 48 x 9 + 6 = 432 + 6 = 438 Hence, verified, (b) 3480+12
Page 24 :
Quotient = 290 290 x 12 = 3480, , Verified, (c) 450 + 7, , Quotient = 64 and remainder = 2 64 x 7 + 2 = 448 + 2 = 450 verified, (d) 900 +10, , Quotient = 90, 90 x 10 = 900 verified, (e) 678÷6
Page 25 :
Quotient = 113 113 x 6 = 678 verified, (f) 2475 ÷11, , Quotient = 225 225 x 11 = 2475, , Verified., 1.Solve the given sums and colour the answers in the grid given below. See, what you find., (a)21×16 = 336, Ans., , (b)15x 7 = 105, (c)93x 2 = 186, (d)17x 5 = 85, (e)10×10 = 100, (f)26×26 = 676, Ans.
Page 26 :
(g)77×10 = 770, (h)50×10 = 500, (i)11×11 = 121, Ans., , (j)59x 7 = 413, (k)31×19 = 58, Ans., , (l)85×30 =2550, (m)64×42 =2688, Ans., , (n)3200÷40=80, (o)19×3 = 57, (p)248÷8 = 31, Ans.
Page 27 :
(q)432÷18=24, Ans., , (r)729 ÷ 9 = 81, (s)825 ÷ 5 =165, (t)221 ÷13 = 17, Ans., , (u)576 ÷12 = 48, Ans.
Page 28 :
(v)288+4=72, Ans., , (w)869÷11=79, Ans., , (x)847÷7=121, Ans.
Page 29 :
(y)981÷3 = 327, Ans., , (z)475÷19 = 25, Ans.
Page 30 :
Chapter 14 How Big? How Heavy?, Page 188, Your Measuring Glass, 1.Now make a guess. Do you think the volume of 10 five-rupee coins will be, more than that of 10 marbles?, Guess the volume of each of these:, Ans., , A ball is nearly 2 marbles., An eraser is nearly 2 marbles., A lemon is nearly 3 marbles., A pencil is nearly 2 marbles., A potato is nearly 4 marbles, 2.Now make your own measuring glass using 35 marbles., Take a glass of water and mark the level of water as ‘O’. Then put in 5
Page 31 :
marbles and mark the level of water as 5 M., Again drop 5 marbles and mark the level of water as 10 M. Likewise make the, markings for 15 M, 20 M, 25 M, 30 M and 35 M., Now put each thing in the measuring glass and check your guess., Try with different things like a matchbox, a stone, etc. and fill the table., Ans., , Page 189, 1.Which has More Volume?, Use your measuring bottle to find out:, (a) What is the volujne of 6 marbles?………………… mL, Ans. 7 mL., (b) What is the volume of 16 one-rupee coins?…………………..mL, Ans. 18 mL., (c) The volume of 24 marbles is………… mL., Ans. 28 mL., (d) The volume of 32 one-rupee coins?………………… mL, Ans. 36 mL., (e) Mollie puts some five-rupee coins in the measuring bottle. How many, coins has she put in it., • If 30 mL water is pushed up?…………………, Ans. 27 coins., • If 60 mL water is pushed up?……………., Ans. 54 coins., 2.First guess and then use your measuring bottle to find out the volume in mL, of, some other things., Ans.
Page 32 :
3.Guess how many litres of water your body will push up?, Ans. About 30 L., Page 190, • Hey! My Math-Magic book is about 26 cm long. So 26 cm cubes will fit along, its length., • And it is about 26 cm wide. So 26 cubes will fit along the width., • So total 520 cm cubes will fit on the Math-Magic book. (26 x 20 = 520 cubes), • Now if all these cubes are arranged in one line then how long will that line, be? 520 cm., Page 191, Practice Time, 1.A stage (platform) is made with 5 Math-Magic books. The volume of this, stage is the same as 520 x 5 = 2600 cm cubes., 2.Guess the volume of these things in cm cubes., • A matchbox is about 24 cm cubes., • A geometry box is about 96 cm cubes., How will you check your guess? Discuss., Ans. Matchbox:, Length = 6 cm, Breadth = 4 cm Height = 1 cm, Hence, Volume = 6x4x1 = 24 cubic cm, , Geometry Box:, Length = 16 cm Width = 6 cm Height = 1 cm, Hence, volume = 16 x 6 x 1 = 96 cubic cm, Matchbox Play –, Tanu is making a stage with matchboxes. She first puts 14 matchboxes like, this in the first layer
Page 33 :
She makes 4 such layers and her stage looks like this., 1.She used___________matchboxes to make this stage., Ans.Number of matchboxes in 1 layer = 14, Hence, number of matchboxes in 4 layers = 14 x 4 = 56, 2.The volume of one matchbox is the same as 10 cm cubes. Then the volume, of this stage is same as________cm cubes., Ans.Volume of 1 matchbox = 10 cubic cm, Hence, volume of 56 matchboxes = 10 x 56 = 560 cubic cm., 3.Which has more volume – your Math-Magic book or Tanu’s platform?, Ans.Tanu’s platform has more volume., 4.With your friends, collect many empty matchboxes of the same size., Measure the sides and write here., , •My matchbox is_____cm wide., Ans. 3 cm, •It is_____ cm long, Ans. 5 cm, •It is_____cm high, Ans. 1 cm, 5.Use 56 matchboxes to make platforms of different heights. Fill this table, Ans., , The volume of each platform is equal to 56 matchboxes., 6.Make deep drawings of the platform^ you have made., Ans.Platform 1:, , Platform 2:
Page 34 :
Page 193, Practice Time, Mohan arranged his matchboxes like this, , 1.How many matchboxes did he use to make it? What is its volume in, matchboxes? …….. matchboxes., Ans. Mohan used 30 matchboxes (16 + 9 + 4 +1 = 30), The volume is 30 matchboxes., 2.Collect empty matchboxes. Arrange them in an interesting way. Make a, deep drawing of it., Ans.One example is given below, , Making A Paper Cube (Activity), Aanan and his friends are making a cube with paper. They cut a sheet of, paper into a square of 91.5 cm side. They cut 6 such squares. Follow these, photos to make your paper cube., 1.Fold the paper into four equal parts to make lines like this., 2.Fold the top left corner and the corner opposite to it like this., 3.Fold the top and bottom edges to meet the centre line. Now fold corner P., 4.So that the paper looks like this., 5.Fold corner Q in the same way. The paper will look like this now., 6.Lift corner P and slip it under the folded paper like this., 7.Do the same for corner Q. The paper will look like this., 8.Turn the paper and fold it to make lines like these.
Page 35 :
9.Each child shoul<J make one such piece. Six children will take their pieces, and put one inside another to make this paper cube., Note: Remember to begin with a square paper of side 19.5 cm. Also, in step 2, you must all start by folding the left corner, , Page 194, How Big is Your Cube?, 1.(a)How long is the side of your cube? 7 cm., (b)How many centimetres cubes can be arranged along its:, •Length? 7 cm, , •Width? 7 cm, •Height? 7 cm, (c) Answer Thimpu’s questions:, •To make the first layer on the table how many cm cubes will I, use?_________, Ans. 49 cm, •How many such layers will I need to make?, Ans.7 such layers., (d) So the total cm cubes = (7x7x7) = 343, (e) The volume of the paper cube is same as cm cubes., Ans.343 cm cubes., 2.Anan made a big cube having double the side of your paper cube. How, many of your paper cubes will fit in it?, Try doing it by collecting all the cubes made in your class., Ans.Side of Anan’s cube = 2 x 7 = 14 cm, We have arranged 2×2 = 4 paper cubes in first layer., And 2 such layers of 4 paper cubes., Hence, we can arrange 4×2 = 8 cubes
Page 36 :
Page 195, Packing Cubes, 1.What is your guess? Who is right? –, Ans. Dinga is right., 2.How can Ganesh and Dinga test their guesses before packing the cubes in, the boxes? Discuss with your friend., Ans.Let us take the first box:, Length = 20 cm, Width = 10 cm, Height = 6 cm Hence, volume = 20 x 10 x 6 =, 1200 cubic cm 12000 cubic cm < 4000 cubic cm, Second Box, Length = 11 cm, Width = 11 cm, Height = 10 cm, Hence, volume = 11 x 11 x 10 = 1210 cubic cm which is less than 4000 cubic, cm, Third Box, Length = 15 cm, Width = 9 cm, Height = 10 cm ,, Hence, volume = 15 x 9 x 10 = 1350 cubic cm which is less than 4000 cubic, cm. Adding the volumes of all these three boxes, we get 1200 + 1210 + 1350, = 3760, This is less than 4000 cubic cm and hence Dinga is right., Page 196, Which Pipe Fills More?, Collect some old postcards. You can also use thick paper of size 14 cm x 9, cm., Fold the postcard along the width to make pipe 1. Join the ends with cello, tape. Take another postcard and fold it along the length to make pipe 2. Join, the ends with tape., 1.Guess which pipe can take more sand inside it. Hold it on a plate and pour, sand to check your guess. Was your guess correct? Discuss., Ans.Pipe 2 can take more sand. This was confirmed during checking., 2. Now do the same with other pipes shown here.To make the triangle, shaped pipe 3, draw two lines on the postcard. Fold the postcard along the, lines. Join the ends with tape., Now make the square-shaped pipe 4.Find out which pipe can take the most, sand inside it. So which pipe has the most volume?, Ans. Square-shaped pipe 4^has more volume.
Page 37 :
Page 197, Trek to Gangotri, (a) For 6 days, each person will need, • Rice and flour =_________g, Ans.100 g + 100 g = 200 g 6 x 200 g = 1200 g, •Pulses =________g, Ans.1/3 of weight of rice and flour, = 1/3 x 1200 = 400 g, •Dried onions =_______g, Ans.10 x 6 g = 60 g, (b) How much of fresh tomatoes should be dried for 6 days for 10 people?, Ans.6 x 10 x 10 = 600 g, (c) What is the total weight of food (for 6 days) in each person’s bag?, Ans., , Page 198, How Heavy Am I?, Do you remember the story of how Vaidika’s daughter found the weight of an
Page 38 :
elephant?, 1.Can you guess the weight of the heaviest animal on this earth? No, it’s not, me. I weigh only 5000 kg! It is the Blue Whale. Its weight is around 35 times, more than me. So how many thousand kg does it weigh?, Ans.The weight of Blue Whale = 35 x 5000 = 175000 kg, 2.Guess how many children of your weight will be equal to the weight of an, elephant of 5000 kg., Ans.Let us assume that weight of one child = 40 kg, Then number of children equal to weight of an elephant = 5000 + 40 = 1250, 3.At birth, a baby elephant weighs around 90 kg. How much did you weigh, when you were born? Find out. How many times is a baby elephant heavier, than you were at birth?, Ans.Baby elephant’s weight = 90 kg, My weight at the time of birth = 3 kg So, baby elephant is; 90 3 = 30 times, heavier, 4.If a grown up elephant eats 136 kg of food in a day then it will eat around, ___________ kg in a month., Guess about how much it will eat in a year., Ans.Food in a day = 136 kg, Hence, food in a month = 136 x 30 = 4080 kg And food in a year = 4080 x 12, = 48960 kg, page 199, Shahid Saves the Bank!, Shahid works in a bank. He sits at the cash counter. Whenever there are too, many coins he does not count them. He just weighs them, , 1.How many coins are there in a sack of 5 rupee coins if it weighs:, (a) 18 kg?, Ans.18 kg = 18 x 1000 g = 18000 g Weight of 1 coin = 9 g, Hence, number of coins in 18000 g = 18000 ÷ 9 = 2000 coins, (b) 54 kg?, Ans.54 kg = 54 x 1000 = 54000 g, Number of coins in 54000 g = 54000 9 = 6000 coins, (c) 4500 kg?, Ans.4500 kg = 4500 x 1000 = 4500000 g, Number of coins in 4500000 g = 4500000 ÷ 9 = 900000 coins, (d)2 kg and 250 g?, Ans.2 kg and 250 g = 2 x 1000 g + 250 g = 2000 + 250 = 2250 g Number of, coins = 2250 ÷ 9 = 250 coins
Page 39 :
(e)1 kg and 125 g?, Ans.1 kg and 125 g, = 1 x 1000 g + 125 g = 1125 g Number of coins = 1125 ÷ 9 = 125 coins, 2.2250 g can also be written as 2 kg and 250 g. Can you explain why?, Ans.We know that 1 kg = 1000 g, When 2250 g is divided by 1000; we get 2 as quotient and 250 as remainder., Hence, it can also be written as 2 kg and 250 g, 3.A 2 rupee coin weighs 6 g. What is the weight of a sack with:, (a) 2200 coins?, Ans.‘Weight of 1 coin = 6 g, Hence, weight of 2200 coins, = 2200 x 6 = 13200 g = 13 kg and 200 g, (b)3000 coins •, Ans. Weight of 3000 coins, = 3000xx 6 = 18000 g = 18 kg, 4.If 100 one rupee coins weigh 485 g, then how much will 10000 coins weigh?, Ans.Since 100 one rupee coins weigh 485 gm .,, Hence, weight of 1 coin = 485÷100, Hence, weight of 10000 coins = (485 ÷ 100) x 10000 = 485 x 100, = 48500 = 48 kg and 500 g., Page 200, Find Out And Discuss, 1.How do people who cannot see make out different notes and coins?, (Hint: Look for a shape, on notes of? 20, 50,100, 500, etc. and feel, it.) Ans. They can recognize different notes by feeling and touching them., Their sense of touch is well developed. Shapes, mentioned above, are made, to assist blind people in recognizing a note., What should we look for to check if a 100 rupee note is real or fake?, Ans. We may check the following:, , (i) Shape, size, paper Hi) Style of printing, (iii) Water mark (The white area with Gandhi’s image), (iv) (Bharat; in Hindi), RBI on the shiny security thread.
