Decimals (IV)
Dividing by 10, 100 and 1000, and by 0.1, 0.01 and 0.001, by moving the decimal point; dividing a decimal by a whole number, and whole numbers that give a decimal; making the divisor a whole number to divide by a decimal; mixed operations with decimals, multiplying and dividing before adding and subtracting and working out brackets first; rounding a quotient to a given number of decimal places; estimating; and word problems.
Key words
| Chinese | English |
|---|---|
| 除數 | divisor |
| 被除數 | dividend |
| 商 | quotient |
| 近似值 | approximate value |
| 小數位 | decimal place |
| 估算 | estimate |
The 10 short lessons and the chapter test
Lessons are in Chinese for now.
- 除以 10、100 和 1000
- 除以 0.1、0.01 和 0.001
- 小數除以整數
- 整數除以整數
- 整數除以小數
- 小數除以小數
- 四則混合計算
- 近似值
- 估算
- 應用題
- 章節測驗 (chapter test)
Sample questions (in Chinese)
Question 1計算。
74.16 ÷ 100 =
Answer and explanation
答案：74.16 ÷ 100 = 0.7416
為甚麼？除以 100，小數點向左移兩個位；位數不夠，要在前面補 0：74.16 ÷ 100 = 0.7416。
Question 2計算。
9.354 ÷ 0.01 =
Answer and explanation
答案：9.354 ÷ 0.01 = 935.4
為甚麼？除以 0.01 等於乘以 100，小數點向右移兩個位：9.354 ÷ 0.01 = 935.4。
Question 3計算。
7.41 ÷ 13 =
Answer and explanation
答案：7.41 ÷ 13 = 0.57
為甚麼？用直式計算，商的小數點要和被除數的小數點對齊：7.41 ÷ 13 = 0.57。驗算：0.57 × 13 = 7.41。
Question 4計算。
91 ÷ 5.6 =
Answer and explanation
答案：91 ÷ 5.6 = 16.25
為甚麼？除數是小數，先把除數和被除數同時乘以 10，除數變成整數，商不變：91 ÷ 5.6 = 910 ÷ 56。所以 91 ÷ 5.6 = 910 ÷ 56 = 16.25。
Based on learning unit 6N1 of the Education Bureau’s Primary Mathematics Curriculum (2017).