SG 
VN 
Length
Length is the measurement of how long, how short an item is or how far away 2 destinations are. The units for length we learn at P3 are centimetres (\(\text{cm}\)), metres (\(\text{m}\)), and kilometres (\(\text{km}\)).
In this article, the learning objectives are:
- Comparison of length based on figures
- Conversion of length from \(\text{m}\) to \(\text{cm}\) and vice versa
- Conversion of length from \(\text{km}\) to \(\text{m}\) and vice versa
- Comparison of length
1. Comparison of length based on figures
Question 1:
Which string is the shortest?
- String X
- String Y
- String Z
Solution:
String X is the shortest.
String Z has the most curls. String Z is the longest.
Hint: Imagine if all the strings are straight.
Answer:
(1) String X
Question 2:
Which line is the longest?
- Line A
- Line B
- Line C
- Line D
Answer:
(3) Line C
Question 3:
Which of the following is the shortest?
- W
- X
- Y
- Z
Answer:
(1) W
Question 4:
Arrange the strings in order of their lengths, beginning with the shortest.
- D, A, C, B
- B, A, C, D
- B, C, A, D
- C, B, A, D
Answer:
4) C, B, A, D
2. Conversion of length from m to cm and vice versa
To convert length from metres to centimetres and vice versa, we need to remember that:
\(1 \text{ m} = 100 \text{ cm}\)
Question 1:
Convert the following to centimetres.
\(2 \text{ m } = \text{__________} \text{ cm }\)
Solution:
\(2 \text{ m} = 200 \text{ cm}\)
Answer:
\(200 \text{ cm }\)
Question 2:
Convert the following to centimetres.
\(12 \text{ m } = \text{ __________} \text{ cm }\)
Solution:
\(12 \text{ m } = 1200 \text{ cm } \)
Answer:
\(1200 \text{ cm }\)
Question 3:
Convert the following to centimetres.
\(6 \text{ m } 10 \text{ cm } = \text{ __________} \text{ cm } \)
Solution:
\(6 \text{ m } 10 \text{ cm }\)
\(= 600 \text{ cm } + 10 \text{ cm }\)
\(= 610 \text{ cm }\)
Answer:
\(610 \text{ cm }\)
Question 4:
Convert the following to centimetres.
\(9 \text{ m } 5 \text{ cm } = \text{ __________} \text{ cm } \)
Solution:
\(9 \text{ m } 5 \text{ cm } \)
\(= 900 \text{ cm } + 5 \text{ cm }\)
\(= 905 \text{ cm }\)
Answer:
\(905 \text{ cm } \)
Question 5:
Convert the following to centimetres.
\(12 \text{ m } 45 \text{ cm } = \text{ __________} \text{ cm } \)
Solution:
\(12 \text{ m } 45 \text{ cm } \)
\(= 1200 \text{ cm } + 45 \text{ cm }\)
\(= 1245 \text{ cm }\)
Answer:
\(1245 \text{ cm }\)
Question 6:
Convert the following to centimetres.
\(83 \text{ m } 7 \text{ cm } = \text{ __________} \text{ cm } \)
Solution:
\(83 \text{ m } 7 \text{ cm } \)
\(= 8300 \text{ cm } + 7 \text{ cm }\)
\(= 8307 \text{ cm }\)
Answer:
\(830 \text{ cm }\)
Question 7:
Convert the following to centimetres.
\(10 \text{ m } 8 \text{ cm } = \text{ __________} \text{ cm } \)
Solution:
\(10 \text{ m } 8 \text{ cm }\)
\(= 1000 \text{ cm } + 8 \text{ cm }\)
\(= 1008 \text{ cm }\)
Answer:
\(1008 \text{ cm }\)
Question 8:
Convert the following to metres.
\(300 \text{ cm } = \text{ __________} \text{ m }\)
Solution:
\(300 \text{ cm } = 3 \text{ m } \)
Answer:
\(3 \text{ m }\)
Question 9:
Convert the following to metres.
\(1400 \text{ cm } = \text{ __________} \text{ m } \)
Solution:
\(1400 \text{ cm } = 14 \text{ m } \)
Answer:
\(14 \text{ m }\)
Question 10:
Convert the following to metres.
\(400 \text{ cm } = \text{ __________} \text{ m } \)
Solution:
\(400 \text{ cm } = 4 \text{ m }\)
Answer:
\(4 \text{ m }\)
Question 11:
Convert the following to metres and centimetres.
\(4000 \text{ cm } = \text{ __________} \text{ m } \text{ __________} \text{ cm }\)
Solution:
\(4000 \text{ cm } = 4 \text{ m } 0 \text{ cm }\)
Answer:
\(4 \text{ m } 0 \text{ cm }\)
Question 12:
Convert the following to metres and centimetres.
\(480 \text{ cm } = \text{ __________} \text{ m } \text{ __________} \text{ cm }\)
Solution:
\(480 \text{ cm }\)
\(= 400 \text{ cm } + 80 \text{ cm }\)
\(= 4 \text{ m } 80 \text{ cm }\)
Answer:
\(4 \text{ m } 80 \text{ cm }\)
Question 13:
Convert the following to metres and centimetres.
\(457 \text{ cm } = \text{ __________} \text{ m } \text{ __________} \text{ cm }\)
Solution:
\(457 \text{ cm }\)
\(= 400 \text{ cm } + 57 \text{ cm }\)
\(= 4 \text{ m } 57 \text{ cm }\)
Answer:
\(4 \text{ m } 57 \text{ cm }\)
Question 14:
Convert the following to metres and centimetres.
\(208 \text{ cm } = \text{ __________} \text{ m } \text{ __________} \text{ cm }\)
Solution:
\(208 \text{ cm}\)
\(= 200 \text{ cm } + 8 \text{ cm }\)
\(= 2 \text{ m } 8 \text{ cm }\)
Answer:
\(2 \text{ m } 8 \text{ cm }\)
3. Conversion of length (km to m and vice versa)
To convert length in kilometres to metres and vice versa, we need to remember that:
\( 1 \text{ km } = 1000 \text{ m} \)
Question 1:
Convert the following to metres.
\(2 \text{ km } = \text{ __________} \text{ m } \)
Solution:
\(2 \text{ km } = 2000 \text{ m }\)
Answer:
\(2000 \text{ m }\)
Question 2:
Convert the following to metres.
\(3 \text{ km } 500 \text{ m } = \text{ __________} \text{ m }\)
Solution:
\(3 \text{ km } 500 \text{ m } \)
\(= 3000 \text{ m } + 500 \text{ m }\)
\(= 3500 \text{ m }\)
Answer:
\(3500 \text{ m }\)
Question 3:
Convert the following to metres.
\(7 \text{ km } 24 \text{ m } = \text{ __________} \text{ m } \)
Solution:
\(7 \text{ km } 24 \text{ m } \)
\(= 7000 \text{ m } + 24 \text{ m }\)
\(= 7024 \text{ m }\)
Answer:
\(7024 \text{ m }\)
Question 4:
Convert the following to metres.
\(6 \text{ km } 4 \text{ m } = \text{ __________} \text{ m } \)
Solution:
\(6 \text{ km } 4 \text{ m } \)
\(= 6000 \text{ m } + 4 \text{ m }\)
\(= 6004 \text{ m }\)
Answer:
\(6004 \text{ m }\)
Question 5:
Convert the following to metres.
\(8 \text{ km } 620 \text{ m } = \text{_________________} \text{ m } \)
Solution:
\(8 \text{ km } 620 \text{ m } \)
\(= 8000 \text{ m } + 620 \text{ m }\)
\(= 8620 \text{ m }\)
Answer:
\(8620 \text{ m }\)
Question 6:
Convert the following to metres.
\(9 \text{ km } 20 \text{ m } = \text{ __________} \text{ m } \)
Solution:
\(9 \text{ km } 20 \text{ m }\)
\(= 9000 \text{ m } + 20 \text{ m }\)
\(= 9020 \text{ m }\)
Answer:
\(9020 \text{ m } \)
Question 7:
Convert the following to metres.
\(7 \text{ km } 7 \text{ m } = \text{ __________} \text{ m }\)
Solution:
\(7 \text{ km } 7 \text{ m }\)
\(= 7000 \text{ m } + 7 \text{ m }\)
\(= 7007 \text{ m }\)
Answer:
\(7007 \text{ m }\)
Question 8:
Convert the following to kilometres.
\(3000 \text{ m } = \text{ __________} \text{ km }\)
Solution:
\(3000 \text{ m } = 3 \text{ km }\)
Answer:
\(3 \text{ km }\)
Question 9:
Convert the following to kilometres.
\(5000 \text{ m } = \text{ __________} \text{ km } \)
Solution:
\(5000 \text{ m } = 5 \text{ km } \)
Answer:
\(5 \text{ km }\)
Question 10:
Convert the following to kilometres and metres.
\(4080 \text{ m } = \text{ __________} \text{ km } \text{ __________} \text{ m } \)
Solution:
\(4080 \text{ m }\)
\(= 4000 \text{ m } + 80 \text{ m }\)
\(= 4 \text{ km } 80 \text{ m }\)
Answer:
\(4 \text{ km } 80 \text{ m }\)
Question 11:
Convert the following to kilometres and metres.
\(8700 \text{ m } = \text{ __________} \text{ km } \text{ __________} \text{ m } \)
Solution:
\(8700 \text{ m }\)
\(= 8000 \text{ m } + 700 \text{ m }\)
\(= 8 \text{ km } 700 \text{ m }\)
Answer:
\(8 \text{ km } 700 \text{ m }\)
Question 12:
Convert the following to kilometres and metres.
\(4055 \text{ m } = \text{ __________} \text{ km } \text{ __________} \text{ m } \)
Solution:
\(4055 \text{ m }\)
\(= 4000 \text{ m } + 55 \text{ m }\)
\(= 4 \text{ km } 55 \text{ m }\)
Answer:
\(4 \text{ km } 55 \text{ m }\)
Question 13:
Convert the following to kilometres and metres.
\(9022 \text{ m } = \text{ __________} \text{ km } \text{ __________} \text{ m }\)
Solution:
\(9022 \text{ m }\)
\(= 9000 \text{ m } + 22 \text{ m }\)
\(= 9 \text{ km } 22 \text{ m }\)
Answer:
\(9 \text{ km } 22 \text{ m }\)
Question 14:
Convert the following to kilometres and metres.
\(3008 \text{ m } = \text{ __________} \text{ km } \text{ __________} \text{ m } \)
Solution:
\(3008 \text{ m }\)
\(= 3000 \text{ m } + 8 \text{ m }\)
\(= 3 \text{ km } 8 \text{ m }\)
Answer:
\(3 \text{ km } 8 \text{ m }\)
4. Comparison of length
Convert all the lengths to the same units before comparing.
Question 1:
Which of the following is the shortest?
- 7 m 7 cm
- 70 cm
- 770 cm
- 7 m
Solution:
\(7 \text{ m } 7 \text{ cm }\)
\(= 700 \text{ cm } + 7 \text{ cm } \)
\(= 707 \text{ cm }\)
\(7 \text{ m } = 700 \text{ cm }\)
Answer:
(2) \(70 \text{ cm }\)
Question 2:
Which of the following is the longest?
- 8 km 80 m
- 808 m
- 880 m
- 8 km 8 m
Solution:
\(8 \text{ km } 80 \text{ m }\)
\(= 8000 \text{ m } + 80 \text{ m } \)
\(= 8080 \text{ m }\)
\(8 \text{ km } 8 \text{ m }\)
\(= 8000 \text{ m } + 8 \text{ m } \)
\(= 8008 \text{ m }\)
Answer:
(1) \(8 \text{ km } 80 \text{ m }\)
Question 3:
Arrange the following in ascending order
\(1 \text{ m } 30 \text{ cm}, 103 \text{ cm}, 139 \text{ cm}, 13 \text{ m }\)
Solution:
\(1 \text{ m } 30 \text{ cm }\)
\(= 100 \text{ cm } + 30 \text{ cm } \)
\(= 130 \text{ cm }\)
\(13 \text{ m } = 1300 \text{ cm }\)
Arranging in ascending order is arranging from the smallest to the greatest.
\(103 \text{ cm}, 1 \text{ m } 30 \text{ cm}, 139 \text{ cm}, 13 \text{ m }\)
Answer:
\(103 \text{ cm}, 1 \text{ m } 30 \text{ cm}, 139 \text{ cm}, 13 \text{ m }\)
Question 4:
Arrange the following in descending order
\(4 \text{ m}, 4 \text{ m } 5 \text{ cm}, 450 \text{ cm}, 40 \text{ cm }\)
Solution:
\(4 \text{ m } = 400 \text{ cm }\)
\(4 \text{ m } 5 \text{ cm }\)
\(= 400 \text{ cm } + 5 \text{ cm } \)
\(= 405 \text{ cm }\)
Arranging in descending order is arranging from the greatest to the smallest.
\(450 \text{ cm}, 4 \text{ m } 5 \text{ cm}, 4 \text{ m}, 40 \text{ cm }\)
Answer:
\(450 \text{ cm}, 4 \text{ m } 5 \text{ cm}, 4 \text{ m}, 40 \text{ cm }\)
Question 5:
Arrange the following in ascending order
\(5022 \text{ m}, 5 \text{ km } 202 \text{ m}, 5 \text{ km } 220 \text{ m}, 5002 \text{ m }\)
Solution:
\(5 \text{ km } 202 \text{ m }\)
\(= 5000 \text{ m } + 202 \text{ m } \)
\(= 5202 \text{ m }\)
\(5 \text{ km } 220 \text{ m }\)
\(= 5000 \text{ m } + 220 \text{ m } \)
\(= 5220 \text{ m }\)
Arranging in ascending order is arranging from the smallest to the greatest.
\(5002 \text{ m}, 5022 \text{ m}, 5 \text{ km } 202 \text{ m}, 5 \text{ km } 220 \text{ m }\)
Answer:
\(5002 \text{ m}, 5022 \text{ m}, 5 \text{ km } 202 \text{ m}, 5 \text{ km } 220 \text{ m }\)
Question 6:
Arrange the following in descending order
\(9 \text{ km } 990 \text{ m}, 9099 \text{ m}, 9909 \text{ m}, 9 \text{ km } 9 \text{ m }\)
Solution:
\(9 \text{ km } 990 \text{ m }\)
\(= 9000 \text{ m } + 990 \text{ m } \)
\(= 9990 \text{ m }\)
\(9 \text{ km } 9 \text{ m }\)
\(= 9000 \text{ m } + 9 \text{ m } \)
\(= 9009 \text{ m }\)
Arranging in descending order is arranging from the greatest to the smallest.
\(9 \text{ km } 990 \text{ m}, 9909 \text{ m}, 9099 \text{ m}, 9 \text{ km } 9 \text{ m }\)
Answer:
\(9 \text{ km } 990 \text{ m}, 9909 \text{ m}, 9099 \text{ m}, 9 \text{ km } 9 \text{ m }\)
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