Tenths And Hundredths
Questions with (*) sign are open-ended questions.
Page 134
What was the length of the smallest pencil you have used?
Ans: The length of the smallest pencil that I used is 4 cm.
How long is this pencil? Guess 3 cm
Measure it using a scale. How good is your guess?
Ans: The length of the pencil is 3.5 cm.
Page 135
What is the length of this pencil?
Ans: 6 mm.
What is its length in centimetres?
Ans: 0.6 cm.
What does 0.9 cm mean? It is the same as 9 millimetres. We can also say this is nine-tenths of a cm. Right?
Ans: 9 m = 0.9 cm
Yes this is nine-tenths of a cm.
So 30.5 cm is the same as 30 cm and 5 millimetres.
About how many of the big frogs will fit on the 1m scale?
Ans: Big frog has a length of 30.5 cm
1 m = 100 cm
Divide 100 by 30 quotient is 3
3 big frogs will fit on the 1m scale.
If they sit in a straight line about how many of the small frogs will cover 1m?
Length of the small frog is 0.9 cm
0.9 cm = 9 mm
1m = 100 cm = 1000 mm
Divide 1000 by 9 then quotient is 111
111 small frogs can cover 1m.
Practice time
1) Length of the nail is 2 cm and 9 mm or 2.9 cm.
Page 136
The length of this lady’s finger (bhindi) is 8 cm and 3 mm. We can also write it as 8.3 cm.
3) Using the scale on this page find the difference in length between candle 1 and candle 3.
| Length of | Length in cm and mm | Length in cm |
| Candle 1 | ||
| Flame 1 | ||
| Candle 2 | ||
| Flame 2 | ||
| Candle 3 | ||
| Flame 3 |
Guess and Colour
First colour the rods as shown, without measuring! Then check.
Rods of length less than 1 cm Red
Rods of length between1 cm and 2 cm Blue
Rods of length between 2 cm and 3 cm Green
Rods of length between 3 cm and 4 cm Orange
Page 137
Guess, Draw and Measure
Guess the lengths to draw these things. Ask your friend to draw the same. After you make the drawing use a scale to measure the length. Whose drawing showed a better guess?
| Guess its length and draw | Measure your drawing | Measure your friend’s drawing |
| An ant of length less than 1 cm | 0.8 cm | 1.2 cm |
| Pencil of length about 7 cm | 6.5 cm | 6.8 cm |
| A glass 11 cm high with water upto 5 cm | 11.2 cm and 4.8 cm | 11.1 cm and 5.2 cm |
| A bangle of perimeter 20 cm | 19.2 cm | 20.4 cm |
| A curly hair of length 16 cm | 15.3 cm | 15.7 cm |
Our Eyes Get Confused?
Which line is longer? A or B? Measure each line and write how long it is in centimetres. How good is your guess?
I think line A is longer.
Measure of line A = 4.6 cm
Measure of line B = 4.6 cm
Which line is longer? C or D? Measure each line.
I think line C is longer.
Measure of line C = 3.2 cm
Measure of line D = 3.2 cm
How good is your guess?
Page 138
Whose Tail is the Longest?
Guess whose tail is the longest. Now measure the tails. How good is your guess?
Ans: I think the monkey’s tail is the longest.
Length of the tail of lizard = 1.7 cm
Length of the tail of rat = 1.3 cm
Length of the tail of cat = 1.2 cm
Length of the tail of puppy = 0.8 cm
Length of the tail of monkey = 2.2 cm
Length of the tail of pig = 1 cm
The Longest Rupee Notes?
What is the length of a 100 rupee note? Guess.
Ans: I guess the length of a 100 rupee note is 15 cm.
Now measure it using a scale.
Now guess the length and width of many other things. Measure and find the difference between your measure and your guess.
| Size of | My guess in cm | Actual measurement in cm | ||
| Length | Width | Length | Width | |
| 100 rupee note | ||||
| 10 rupee note | ||||
| 20 rupee note | ||||
| 5 rupee note | ||||
| Post card | ||||
| Math-magic book | ||||
Page 139
1) How many paise does a matchbox cost?
Ans: 50 paise
2) How many matchboxes can be got for ` 2.50?
Ans: 5 match boxes
3) How many rupees does the soap cost?
Ans: ₹ 8.75
4) Arun wanted to buy a soap. He has a five-rupee coin, 2 one-rupee coins and 4 half-rupee coins. Write in rupees what money he will get back.
Money with Arun = (₹5 X 1)+ (₹1 X 2) + (0.5 X 4)
= 5 + 2 + 2
= ₹ 9.
Cost of one soap = ₹ 8.75
Money that Arun will get back = ₹9 – ₹ 8.75
= 900 paise – 875 paise
= 25 paise
= ₹0.25
5 a) An egg costs two and a half rupees. How much will one and a half dozen cost?
Cost of one egg = ₹ 2.50
One and half dozen means = 12 + 6 = 18
Cost of 18 eggs = 18 X 2.50
= ₹ 45
Money left with Kannan = 60 – 45
= ₹ 15.
b) How many pens can Kannan buy? How much money is left?
Cost of a pen = ₹ 6.50
Cost of 2 pens = ₹ 6.50 X 2
= ₹ 13
Mount with Kannan = ₹ 15 – ₹13
= ₹ 2.
6) The price of two pens is ₹13. Can she buy two pens?
Ans: Yes, she can buy two pens.
Page 140
Practice time—Match these
Match each yellow box with one green and one pink box
Colourful Design
What part of this sheet is coloured blue?
Ans: 1/10
What part of the sheet is green?
Ans: 3/10
Which colour covers 0.2 of the sheet?
Ans: Yellow
Now, look at the second sheet. Each strip is divided into 10 equal boxes. How many boxes are there in all?
Ans: There are total 100 boxes.
Is each box 1/100 part of the sheet?
Ans: Yes.
How many blue boxes are there?
Ans: 10.
Is blue equal to 10/100 of the sheet? We saw that blue is also equal to 1/10 of the sheet. We wrote it as 0.1 of the sheet.
Ans: Yes, blue equal to 10/100 of the sheet.
Page 141
Can we say 10/100 = 1/10 = 0.10 = 0.1?
Ans: Yes.
Think: can we write 10 paise as 0.1 of a rupee?
(Hint: remember we wrote 99 paise as 0.99 rupee!)
Ans: Yes, we can write.
How many boxes are red? What part of the sheet is this?
Ans: 15 boxes are red. This is 15/100 part.
Now 3/100 of the sheet is black. We can say 0.03 sheet is black.
How many white boxes are there in the sheet?
Ans: 22 boxes.
What part of the second sheet is white?
Ans: 22/100.
Make a nice design by colouring 0.45 part of this square red. Use four colours. Each colour should cover 0.05 of the square.
Teena jumped 3.50m which is 3 m and 50 cm. But how far did Anu jump?
Ans: 3 m and 5 cm.
Who is the winner in the long jump?
Ans: Rehana is the winner in the long jump.
Page 142
Write the names of I, II and III winners on this stand.
Do you remember that 1 metre = 100 centimetres?
So one centimetre is 1/100 of a metre.
We also write 1 cm as 0.01 m.
Write in Metres
3 metre 45 centimetre 3.05 metres
99 centimetre 0.99 metres
1 metre and 5 centimetre 1.05 metres
How Big Can You Get
A)
After breathing out 1.52 m. on taking a deep breath 1.82 m.
Difference in size = 1.82 – 1.52 = 0.30 metre.
B)
You have to grow 45 cm more to reach 2 m in height. What is Dinesh’s height in metres?
1 m 55 cm.
2 m = 200 cm
200 – 45 = 155 cm
= 1 m 55 cm
Page 143
Practice time
1) Currency from different countries
Have you seen any notes or coins used in any other country?
Ans: Yes, I have seen notes and coins used in other countries.
Shivam Bank has a chart to show us how many Indian rupees we can get when we change money of different countries.
A) The currency of which country will cost the most in Indian Rupees?
Ans: England pound will cost the most in Indian Rupees.
B) Mithun’s uncle in America had sent him 10 USA dollars as a gift. Mithun used 350 rupees for a school trip. How much money was left with him?
1 USA dollar = ₹ 39.70
Exchange amount for 10 dollars = 39.70 X 10
= 397.0
= ₹ 397
Money left with Mithun = 397 – 350
= ₹ 47.
C) Majeed’s father is working in U.A.E. He gets 1000 Dirham as salary. Arun’s father who is working in Sri Lanka gets 2000 Sri Lankan Rupees. Who gets more Indian rupees as salary?
Majeed’s father
Salary = 1000 Dirham
1 Dirham = ₹10.80
Value in Indian currency = 10.80 X 1000
= ₹ 10800
Arun’s father
Salary = 2000 SriLankar Rupees
1 SriLankan Rupees = ₹ 0.37
= 0.37 X 2000
= ₹ 740
Majeed’s father gets more Indian rupees as salary.
D) Leena’s aunty brought a present for her from China. It cost 30 Yuan. Find what it costs in Indian rupees.
1 Yuan = ₹ 5.50
Value in Indian currency = 5.50 X 30
= ₹ 165
E) Astha wants some Hong Kong Dollars and Won.
1) How many Won can she change for 4? For 400?
1 Won = ₹ 0.04
Multiply both the sides by 100
1 X 100 = 0.04 X 100
100 = ₹ 4
Astha will get 100 won for ₹4.
₹ 4 = 100 won
₹ 400 = 100 X 100
= ₹ 10000
2) How many Hong Kong Dollars can she change for 508?
1 HK Dollar = ₹5.10
1 Re = 1 ÷ 5.10
₹508 = 508 ÷ 5.10
= 99.61 HK Dollar
2) Kiran went shopping with 200. Look at the bill. The shopkeeper forgot to put the point correctly in the prices. Put the point in the correct place and find out the total amount of the bill.
| Item | Quantity | Price in Rupees |
| Soap
Green gram Tea Coconut oil |
1
1kg 250 gm 1 Litre
|
1250
5025 2725 6000 |
Answer:
| Item | Quantity | Price in Rupees |
| Soap
Green gram Tea Coconut oil |
1
1kg 250 gm 1 Litre
|
12.50
50.25 27.25 60.00 |
| 150.00 |
3). Which city is cool?
Page 145
The temperature in each city was noted at 3 pm on 16 January 2008.
1). Which place had the highest temperature at 3 pm? Which place is the coolest at that time?
Ans: Mumbai had the highest temperature at 3 pm.
Srinagar is the coolest at that time.
2). How much higher is the temperature in Mumbai from that in Srinagar?
Temperature at Mumbai = 35.10 C
Temperature at Srinagar = 8.10 C
Difference in temperature = 35.1- 8.1
= 27.00 C
3). How many degrees will the temperature need to rise for it to reach 400 C in Thiruvananthapuram?
Temperature in Thiruvananthapuram = 33.50 C
40 – 33.5 = 6.50 C
4) How much lower is the temperature of Kolkata from that in Chennai?
Temperature at Kolkata = 26.60 C
Temperature at Chennai = 29.90 C
29.9 – 26.6 = 3.30 C
5) The temperature in these cities was also noted at 3 am on the same day.
Look at the table and answer the questions.
a) Which place had the lowest temperature at 3 am? Imagine yourself to be there and describe how it would feel.
Ans: Srinagar.
b) What is the difference between the temperatures at 3 pm and 3 am in Chennai?In Bhopal?
Chennai
Temperature at 3 am = 29.90 C
Temperature at 3 pm = 21.10 C
Difference = 29.9 – 21.1 = 26.6 = 8.80 C
Bhopal
Temperature at 3 am = 25.90 C
Temperature at 3 pm = 9.80 C
Difference = 25.9 – 9.8 = 16.10 C
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6). Be My multiple, I’ll Be Your Factor
13). Ways To Multiply and Divide
