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Metre, decimetre, centimetre
Textbook: Part 2, lesson 59, pp. 40–41
GoalWrite lengths in mixed units (m, dm, cm); compare, add and subtract them.
New words
height (of a person) · bo‘ytall, high · balandshort, low · pastmixed units · aralash birlik
Explanation
It is easiest to compare lengths in one unit. 1 m 25 cm = 100 cm + 25 cm = 125 cm. 178 cm = 1 m 7 dm 8 cm. For adding and subtracting, first change everything into centimetres: 4 m 5 dm 1 cm = 451 cm. The answer can be split into m, dm, cm again.
Worked examples
4 m 5 dm 1 cm + 2 m 3 dm 8 cm = 451 cm + 238 cm = 689 cm = 6 m 8 dm 9 cm.
7 m 7 dm 3 cm − 1 m 5 dm 2 cm = 773 − 152 = 621 cm = 6 m 2 dm 1 cm.
Class activity
“Our heights”: children measure each other against a paper strip on the wall, write the result as “… m … dm … cm” and “… cm”, then find who is tallest.
Practice
1
1 m 25 cm = ? cm
125
2
Write 178 cm in m, dm, cm.
1 m 7 dm 8 cm
3
Compare: 5 m 6 dm 3 cm and 5 m 4 dm 2 cm.
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4
4 m 5 dm 1 cm + 2 m 3 dm 8 cm = ? cm
689