Samacheer Kalvi Class 4 Maths Solutions Term 1 Chapter 4 Measurements Exercise 4.5

 

Question 1. Convert into cm
(a) 5m
(b) 7m
(c) 9m
(d) 16m
Answer:
(a) \( 5 \text{m} = 5 \times 100 = 500 \text{ cm} \)
(b) \( 7 \text{m} = 7 \times 100 = 700 \text{ cm} \)
(c) \( 9 \text{m} = 9 \times 100 = 900 \text{ cm} \)
(d) \( 16 \text{m} = 16 \times 100 = 1600 \text{ cm} \) When converting from meters to centimeters, we multiply the number of meters by 100, because 1 meter has 100 centimeters. This rule helps us find the equivalent length in a smaller unit.
In simple words: To change meters into centimeters, just multiply the meter number by 100.

🎯 Exam Tip: Remember that 1 meter equals 100 centimeters; this is a key conversion factor for length measurements.

 

Question 2. Convert into m
(a) 6000 cm
(b) 4000 cm
(c) 13000 cm
(d) 17000 cm
Answer:
(a) \( 6000 \text{ cm} = 6000 \div 100 = 60 \text{ m} \)
(b) \( 4000 \text{ cm} = 4000 \div 100 = 40 \text{ m} \)
(c) \( 13000 \text{ cm} = 13000 \div 100 = 130 \text{ m} \)
(d) \( 17000 \text{ cm} = 17000 \div 100 = 170 \text{ m} \) To convert centimeters into meters, we divide the number of centimeters by 100. This is the opposite of converting meters to centimeters and helps us express lengths in larger units.
In simple words: To change centimeters into meters, you just divide the centimeter number by 100.

🎯 Exam Tip: When converting from a smaller unit (cm) to a larger unit (m), always divide, and when converting from a larger unit to a smaller unit, always multiply.

 

Question 3. Add
(a)

(b)
(c)
Answer:
(a)\( 4 \text{m } 75 \text{cm} + 3 \text{m } 18 \text{cm} = 7 \text{m } 93 \text{cm} \)
(b)\( 25 \text{m } 53 \text{cm} + 18 \text{m } 24 \text{cm} = 43 \text{m } 77 \text{cm} \)
(c)\( 48 \text{m } 72 \text{cm} + 14 \text{m } 34 \text{cm} = 63 \text{m } 06 \text{cm} \) To add measurements with meters and centimeters, we add the centimeters first, then the meters. If the sum of centimeters is 100 or more, we convert 100 cm into 1 meter and add it to the meter column.
In simple words: Add the centimeter parts together, then add the meter parts. If centimeters add up to 100 or more, turn every 100 cm into 1 meter and add it to the meters.

🎯 Exam Tip: Always align the meter and centimeter values vertically before adding, and remember to carry over any extra centimeters (100 cm = 1 m) to the meter column.

 

Question 4. Subtract
(a)

(b)
(c)
Answer:
(a)\( 9 \text{m } 28 \text{cm} - 3 \text{m } 14 \text{cm} = 6 \text{m } 14 \text{cm} \)
(b)\( 63 \text{m } 47 \text{cm} - 36 \text{m } 24 \text{cm} = 27 \text{m } 23 \text{cm} \)
(c)\( 96 \text{m } 32 \text{cm} - 20 \text{m } 48 \text{cm} = 75 \text{m } 84 \text{cm} \) To subtract measurements with meters and centimeters, we subtract the centimeters first, then the meters. If the centimeters in the top number are smaller than the bottom number, we borrow 1 meter (which is 100 cm) from the meters column. This increases the centimeters by 100 and decreases the meters by 1. Then we perform the subtraction.
In simple words: Subtract the centimeters, then the meters. If you can't subtract centimeters directly, borrow 1 meter from the meters side, which gives you 100 extra centimeters to use.

🎯 Exam Tip: When borrowing in subtraction, always remember that 1 meter converts to 100 centimeters, not 10, to avoid common errors.

 

Question 5. Raju used 13 m 25 cm ribbon for making his project. If he had bought 20 m of ribbon, How much ribbon is left with him?
Answer:
Total length of ribbon \( = 20 \text{ m} \)
Raju used \( = 13 \text{ m } 25 \text{ cm} \)
To find the ribbon left, we subtract the used length from the total length. Since 20 m can be written as 19 m 100 cm, we can easily subtract 13 m 25 cm.

Remaining length of ribbon \( = 6 \text{ m } 75 \text{ cm} \)
In simple words: Raju had 20 meters of ribbon. He used 13 meters and 25 centimeters. To find out what's left, we take away the ribbon he used from the total. He has 6 meters and 75 centimeters of ribbon left.

🎯 Exam Tip: For word problems involving subtraction with different units, always convert the larger unit to the smaller unit if borrowing is needed, ensuring consistent units for calculation.

 

Question 6. The distance between bus stand and school is 81 m 40 cm and the distance between school and temple is 20 m 10 cm. What is the total distance from bus stand to temple ?
Answer:
Distance between bus stand to school \( = 81 \text{ m } 40 \text{ cm} \)
Distance between school to temple \( = 20 \text{ m } 10 \text{ cm} \)
To find the total distance, we add these two distances. This involves adding the centimeter parts and the meter parts separately.

Total distance between bus stand to temple \( = 101 \text{ m } 50 \text{ cm} \)
In simple words: We need to add the distance from the bus stand to the school and the distance from the school to the temple to find the total distance. We add the meters and centimeters separately to get 101 meters and 50 centimeters.

🎯 Exam Tip: For total distance questions, identify the path and simply add up the individual segments, keeping units consistent and converting if needed for clean sums.

 

Question 7. Arul has a 4 metre long piece of wood. He wants to cut it into 2 equal lengths. How long should each piece be in millimetres?
Answer:
Length of wood \( = 4 \text{ m} \)
First, convert the length of the wood from meters to millimeters. We know that \( 1 \text{ m} = 1000 \text{ mm} \).
So, \( 4 \text{ m} = 4 \times 1000 = 4000 \text{ millimeters} \).
Now, Arul wants to cut it into 2 equal parts. So we divide the total length by 2.
Length of each piece \( = 4000 \div 2 = 2000 \text{ millimeters} \).
In simple words: First, change the 4 meters of wood into millimeters (4000 mm). Then, cut this total length into two equal parts, so each piece will be 2000 millimeters long.

🎯 Exam Tip: Always pay attention to the final unit requested in the question (e.g., millimeters), even if the initial measurements are in different units.

 

Question 8. Amudha knows tailoring. She bought 10 metre long cloth. She needs 4 curtains to be stitched. Each curtain's height is 160cm. Would she be able to stitch all curtains? If some cloth is left behind, how much would it be?
Answer:
Total length of cloth Amudha bought \( = 10 \text{ m} \).
Convert total cloth length to centimeters: \( 10 \text{ m} = 10 \times 100 = 1000 \text{ cm} \).
Height of one curtain \( = 160 \text{ cm} \).
Cloth needed for 4 curtains \( = 4 \times 160 \text{ cm} = 640 \text{ cm} \).
This means \( 640 \text{ cm} = 6 \text{ m } 40 \text{ cm} \).
Since Amudha has \( 1000 \text{ cm} \) of cloth and only needs \( 640 \text{ cm} \), she will be able to stitch all four curtains.
Cloth left behind \( = \text{Total cloth} - \text{Cloth needed} \)
\( = 1000 \text{ cm} - 640 \text{ cm} = 360 \text{ cm} \).
The remaining cloth is \( 360 \text{ cm} \).
In simple words: Amudha has 1000 cm of cloth. She needs 640 cm to make 4 curtains. She can make all curtains because she has enough cloth. After making them, she will have 360 cm of cloth left over.

🎯 Exam Tip: For problems involving multiple steps and unit conversions, convert all measurements to a single, consistent unit early in the calculation to avoid mistakes.