Decimals (V)
Changing decimals into fractions in their simplest form; changing fractions into decimals by making the denominator 10, 100 or 1000, or by dividing the numerator by the denominator; changing mixed numbers into decimals; the common pairs such as 1/2 = 0.5 and 1/4 = 0.25; rounding when the division does not end; and comparing and ordering fractions and decimals by writing them the same way.
Key words
| Chinese | English |
|---|---|
| 分數 | fraction |
| 小數 | decimal |
| 擴分 | expand a fraction |
| 約簡 | simplify |
| 帶分數 | mixed number |
The 5 short lessons and the chapter test
Lessons are in Chinese for now.
- 小數化分數
- 分數化小數
- 常見的分數和小數
- 取近似值
- 比較分數和小數
- 章節測驗 (chapter test)
Sample questions (in Chinese)
Question 1把小數化為分數。（答案要約至最簡；大於 1 的寫成帶分數。）
0.17 =
Answer and explanation
答案：0.17 = 17100
為甚麼？0.17 有兩位小數，寫成分母是 100 的分數：0.17 = 17100。
Question 2把分數擴分，化為小數。
59125 = 1000 =
Answer and explanation
答案：59125 = 4721000 = 0.472
為甚麼？125 × 8 = 1000，分子和分母同時乘以 8：59125 = 4721000 = 0.472。
Question 3用分子除以分母，把分數化為小數。
2125 =
Answer and explanation
答案：2125 = 0.84
為甚麼？2125 = 21 ÷ 25 = 0.84。
Question 4把帶分數化為小數。
2 14 =
Answer and explanation
答案：2 14 = 2.25
為甚麼？先把分數部分化為小數：14 = 1 ÷ 4 = 0.25。所以 2 14 = 2 + 0.25 = 2.25。
Based on learning unit 6N2 of the Education Bureau’s Primary Mathematics Curriculum (2017).