📚 Fractions, Decimals and Percentages: IGCSE Number Skills | 分数、小数与百分数：IGCSE 数字技能
In IGCSE Mathematics, the Number topic tests your ability to move confidently between fractions, decimals and percentages. These three forms describe the same proportional value, and exam questions often mix them in real-life contexts such as discounts, interest, measurement and probability.
在 IGCSE 数学中，数字主题考查你在分数、小数和百分数之间自如转换的能力。这三种形式描述的是同一个比例值，考试题目常常把它们混合在实际情境中，例如折扣、利息、测量和概率。
1. Understanding Equivalent Forms | 理解等价形式
rcentages are equivalent ways of expressing a part of a whole. For example, 1/2 = 0.5 = 50% l parts the whole is divided into, while the numerator tells you how many parts are taken.
分数、小数和百分数是表示“整体的一部分”的等价方式。例如，1/2 = 0.5 = 50%。分数的分母表示整体被分成多少等份，分子表示取了多少份。
A percentage means 'per hundred', so 35% means 35 out of 100, which can be written as the fraction 35/100 or the decimal 0.35. Understanding this link is the foundation for all conversion methods.
百分数表示“每一百”，所以 35% 表示 100 份中的 35 份，可以写成 35/100 或小数 0.35。理解这种联系是所有转换方法的基础。
2. Converting Fractions to Decimals and Percentages | 分数与小数、百分数的互化
= 3 ÷ 8 = 0.375. To convert a decimal to a percentage, multiply by 100: 0.375 × 100 = 37.5%.
要把分数转换为小数，用分子除以分母。例如，3/8 = 3 ÷ 8 = 0.375。要把小数转换为百分数，乘以 100：0.375 × 100 = 37.5%。
To convert a percentage to a decimal, divide by 100. For example, 62% .62. To convert a percentage to a fraction, write it over 100 and simplify if possible: 62% = 62/100 = 31/50.
要把百分数转换为小数，除以 100。例如，62% = 62 ÷ 100 = 0.62。要把百分数转换为分数，先写成 100 分之几，再尽可能约分：62% = 62/100 = 31/50。
3. Ordering Fractions, Decimals and Percentages | 排序分数、小数和百分数
s to the same form, usually decimals or percentages. For example, arrange 2/5, 0.45 and 38% in ascending order: 2/5 = 0.40, 38% = 0.38, so the order is 38%, 2/5, 0.45.
要比较混合形式，先把所有数值转换成同一种形式，通常是小数或百分数。例如，将 2/5、0.45 和 38% 按升序排列：2/5 = 0.40，38% = 0.38，所以顺序为 38%、2/5、0.45。
When fractions have different denominators, either find a common denominator or convert each fraction to a decimal. On the number line, values increase from left to right.
当分数的分母不同时，可以找一个公分母，或者把每个分数转换为小数。在数轴上，数值从左到右依次增大。
4. Adding and Subtracting Fractions | 分数的加减法
or, simply add or subtract the numerators and keep the denominator: 2/9 + 4/9 = 6/9 = 2/3.
要加减同分母的分数，只需加减分子，分母保持不变：2/9 + 4/9 = 6/9 = 2/3。
+ 2/3: the LCD of 4 and 3 is 12, so 1/4 = 3/12 and 2/3 = 8/12, giving 3/12 + 8/12 = 11/12.
如果分母不同，先找最小公分母（LCD）。例如，1/4 + 2/3：4 和 3 的最小公分母是 12，所以 1/4 =
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