Fractions (V)
Fractions as the answer to a division (3 ÷ 4 = 3/4) and as a way to compare two numbers; a fraction divided by a whole number, a whole number by a fraction, and a fraction by a fraction (dividing by a number is multiplying by its reciprocal); up to three numbers with multiplication and division, and mixed operations in the usual order; word problems with remainders, such as how many pens $60 buys and how much is left; and finding the value of one first.
Key words
| Chinese | English |
|---|---|
| 分數除法 | dividing fractions |
| 倒數 | reciprocal |
| 商 | quotient |
| 餘數 | remainder |
| 四則混合計算 | mixed operations |
The 10 short lessons and the chapter test
Lessons are in Chinese for now.
- 分數和除法
- 分數表示比較
- 分數除以整數
- 整數除以分數
- 分數除以分數
- 三個數的乘除
- 四則混合計算
- 商和餘數
- 單一數量
- 應用題
- 章節測驗 (chapter test)
Sample questions (in Chinese)
Question 1把 15 個薄餅平均分給 12 人，每人可分得多少個薄餅？（答案要約至最簡；大於 1 的寫成帶分數。）
每人分得 個。
Answer and explanation
答案：每人分得 1 14 個。
為甚麼？每人分得 15 ÷ 12 個。15 ÷ 12 可以寫成分數 1512：被除數是分子，除數是分母，1512 = 1 14。
Question 2計算。（答案要約至最簡；大於 1 的寫成帶分數。）
1 89 ÷ 9 =
Answer and explanation
答案：1 89 ÷ 9 = 1781
為甚麼？先把帶分數化為假分數：1 89 = 179。整數可以寫成分母是 1 的分數：9 = 91。除以一個數，等於乘以它的倒數：÷ 91 變成 × 19。分子乘分子，分母乘分母：17 × 19 × 9 = 1781。
Question 3計算。（答案要約至最簡；大於 1 的寫成帶分數。）
12 ÷ 58 =
Answer and explanation
答案：12 ÷ 58 = 19 15
為甚麼？整數可以寫成分母是 1 的分數：12 = 121。除以一個數，等於乘以它的倒數：÷ 58 變成 × 85。分子乘分子，分母乘分母：12 × 81 × 5 = 965 = 19 15。
Question 4計算。（答案要約至最簡；大於 1 的寫成帶分數。）
45 ÷ 2 12 =
Answer and explanation
答案：45 ÷ 2 12 = 825
為甚麼？先把帶分數化為假分數：2 12 = 52。除以一個數，等於乘以它的倒數：÷ 52 變成 × 25。分子乘分子，分母乘分母：4 × 25 × 5 = 825。
Based on learning unit 5N5 of the Education Bureau’s Primary Mathematics Curriculum (2017).