📚 Cambridge KS3 Accounting: Formula & Theorem Quick Reference Handbook | 剑桥KS3会计：公式定理速查手册
Mastering the essential formulas and theorems in accounting is the key to analysing business performance and making informed financial decisions. This handbook brings together all the fundamental equations you need for Cambridge KS3 Accounting, from the core accounting equation to profitability and liquidity ratios, depreciation methods, and inventory valuation techniques. Each concept is clearly explained with practical examples and paired in both English and Chinese to support bilingual learning and revision.
掌握会计领域的基本公式与定理，是分析企业业绩并做出明智财务决策的关键。这本手册汇集了剑桥KS3会计课程所需的所有基础等式，从核心的会计等式到盈利能力和流动性比率、折旧方法以及存货计价技术。每个概念均配有清晰解说和实际案例，并以中英双语一一对应呈现，助力双语学习与复习。
1. The Accounting Equation | 会计等式
The accounting equation is the foundation of double-entry bookkeeping. It states that everything a business owns (assets) is financed either by borrowing (liabilities) or by the owner's investment (owner's equity).
会计等式是复式记账法的基石。它表明企业拥有的一切（资产）都是通过借款（负债）或所有者投入（所有者权益）来融资的。
The basic formula is: Assets = Liabilities + Owner's Equity. This relationship must always balance after every transaction.
基本公式为：资产 = 负债 + 所有者权益。每笔交易后，这个等式都必须始终保持平衡。
If a business has assets of £50,000 and liabilities of £20,000, then owner's equity must be £30,000, calculated as £50,000 - £20,000.
若某企业资产为50,000英镑，负债为20,000英镑，则所有者权益必定为30,000英镑，即50,000 - 20,000。
2. Expanded Accounting Equation | 扩展会计等式
The expanded equation shows how profit or loss and drawings affect owner's equity. It links the income statement directly to the statement of financial position.
扩展等式揭示了利润或亏损以及提款如何影响所有者权益，它将利润表与财务状况表直接联系起来。
tal + (Revenue - Expenses) - Drawings. Here, capital is the initial investment, and revenue minus expenses gives net profit.
公式：资产 = 负债 + 资本 + （收入 - 费用） - 提款。其中，资本为初始投资，收入减费用得出净利润。
If capital is £10,000, revenue is £5,000, expenses are £3,000 and drawings are £500, then equity increases by net profit of £2,000 minus drawings, so closing equity is £11,500.
若资本为10,000英镑，收入5,000英镑，费用3,000英镑，提款500英镑，则权益因净利润2,000英镑增加但减去提款后，期末权益为11,500英镑。
3. Income Statement (Profit & Loss) | 利润表（损益表）
The income statement calculates the profit or loss over a period. The key formulas are used to determine gross profit and net profit.
利润表计算一定期间内的利润或亏损。以下关键公式用于计算毛利和净利润。
Sales. Cost of sales represents the direct cost of goods sold, such as purchases adjusted for opening and closing inventory.
毛利 = 销售收入 - 销售成本。销售成本代表已售商品的直接成本，例如进货额经期初和期末存货调整后的数额。
nses. Other expenses include rent, salaries, and advertising. A positive net profit means the business earned more than it spent.
净利润 = 毛利 - 其他费用。其他费用包括租金、工资和广告费等。净利润为正表示企业盈利。
If a shop sells goods for £100,000 and the cost of those goods is £60,000, gross profit is £40,000. If additional expenses total £25,000, net profit is £15,000.
若某商店销售收入为100,000英镑，售出商品成本为60,000英镑，则毛利为40,000英镑。若其他费用合计25,000英镑，则净利润为15,000英镑。
4. Cost of Sales Calculation | 销售成本计算
Cost of sales is not simply purchases; it must consider inventory changes. The formula helps match costs to the sales made during the period.
销售成本不仅仅是进货额，还必须考虑存货变动。这一公式有助于将成本与当期实现的销售匹配。
ntory + Purchases - Closing Inventory. Sometimes carriage inwards is added to purchases if goods are purchased with delivery charges.
公式：销售成本 = 期初存货 + 进货 - 期末存货。如果购货包含运费，有时还需将购货运费加入进货。
A business starts with £5,000 of inventory, buys £20,000 more, and ends with £4,000. The cost of sales is £5,000 + £20,000 - £4,000 = £21,000.
某企业期初存货5,000英镑，本期进货20,000英镑，期末存货4,000英镑，则销售成本为5,000 + 20,000 - 4,000 = 21,000英镑。
5. Gross Profit Margin | 毛利率
The gross profit margin measures how efficiently a business turns sales into profit before overheads. It is expressed as a percentage.
毛利率衡量企业在扣除间接费用之前将销售收入转化为利润的效率，以百分比表示。
Formula: Gross Profit Margin = (Gross Profit / Sales Revenue) × 100%. A higher margin suggests better control of direct costs or strong pricing power.
公式：毛利率 = （毛利 / 销售收入） × 100%。毛利率越高，表明直接成本控制越好，或定价能力越强。
If sales are £80,000 and gross profit is £32,000, the margin is (32,000 / 80,000) × 100% = 40%. This means 40 pence of every £1 sale is gross profit.
若销售收入为80,000英镑，毛利为32,000英镑，则毛利率为（32,000 / 80,000）× 100% = 40%。这表示每1英镑销售收入中有40便士是毛利。
6. Net Profit Margin | 净利率
The net profit margin shows the percentage of sales revenue left after all expenses are deducted. It reflects overall profitability and expense management.
净利率显示扣除所有费用后剩余的销售收入百分比，它反映整体盈利能力和费用管理状况。
Formula: Net Profit Margin = (Net Profit / Sales Revenue) × 100%. Unlike gross margin, this takes into account all operating costs and overheads.
公式：净利率 = （净利润 / 销售收入） × 100%。与毛利率不同，净利率考虑了所有运营成本和间接费用。
A net profit of £12,000 on sales of £120,000 gives a net margin of 10%. It tells stakeholders how much net profit is generated per pound of sales.
销售收入120,000英镑，净利润12,000英镑，则净利率为10%。它向利益相关者显示每英镑销售收入产生了多少净利润。
7. Statement of Financial Position (Balance Sheet) | 财务状况表（资产负债表）
The statement of financial position is based on the accounting equation. It lists assets, liabilities, and equity at a specific point in time.
财务状况表以会计等式为基础，列示特定时点的资产、负债和权益。
urrent Assets. Current assets include cash, inventory, and receivables; non-current assets include property and equipment.
总资产 = 流动资产 + 非流动资产。流动资产包括现金、存货和应收账款；非流动资产包括房产和设备。
ties + Non-current Liabilities. Equity includes capital and retained earnings. The two sides must always balance.
总负债 = 流动负债 + 非流动负债。权益包括资本和留存收益。两边必须始终平衡。
If non-current assets are £50,000, current assets £30,000, current liabilities £15,000 and non-current liabilities £25,000, then equity is £50,000 + £30,000 - £15,000 - £25,000 = £40,000.
若非流动资产为50,000英镑，流动资产为30,000英镑，流动负债15,000英镑，非流动负债25,000英镑，则权益为50,000 + 30,000 - 15,000 - 25,000 = 40,000英镑。
8. Current Ratio (Working Capital Ratio) | 流动比率（营运资金比率）
The current ratio assesses a business's ability to pay short-term obligations using its current assets. It is a key measure of liquidity.
流动比率评估企业运用流动资产偿还短期债务的能力，是衡量流动性的关键指标。
ets / Current Liabilities. A ratio of 2:1 is often considered safe, indicating the business can cover its debts twice.
公式：流动比率 = 流动资产 / 流动负债。一般认为2:1的比率较为安全，这意味着企业有足够资金偿还两倍债务。
If current assets are £18,000 and current liabilities are £9,000, the ratio is 2:1. A ratio below 1 suggests potential difficulty meeting payments.
若流动资产为18,000英镑，流动负债为9,000英镑，则比率为2:1。比率低于1说明可能面临付款困难。
9. Acid Test Ratio (Quick Ratio) | 酸性测试比率（速动比率）
The acid test ratio is a stricter liquidity measure because it excludes inventory, which may not be quickly converted to cash.
酸性测试比率是一个更严格的流动性衡量指标，因为它排除了可能无法迅速变现的存货。
ent Assets - Inventory) / Current Liabilities. Ideally, this ratio should be at least 1:1.
公式：酸性测试比率 = （流动资产 - 存货） / 流动负债。该比率理想上应至少为1:1。
If current assets total £20,000, inventory is £8,000, and current liabilities are £10,000, the quick assets are £12,000. The ratio is 12,000 / 10,000 = 1.2:1.
若流动资产共20,000英镑，存货8,000英镑，流动负债10,000英镑，则速动资产为12,000英镑，比率为12,000 / 10,000 = 1.2:1。
10. Straight-Line Depreciation | 直线折旧法
Depreciation spreads the cost of a non-current asset over its useful life. The straight-line method charges an equal amount each year.
折旧将非流动资产成本分摊至其使用寿命内。直线法每年计提等额折旧。
Value) / Useful Life. Residual value is the estimated scrap value at the end of its life.
公式：年折旧费用 = （成本 - 残值） / 使用寿命。残值是指资产在寿命结束时的估计废料价值。
A machine bought for £10,000 with an expected useful life of 5 years and a residual value of £1,000 has annual depreciation of (10,000 - 1,000) / 5 = £1,800.
一台机器购价10,000英镑，预计使用寿命5年，残值1,000英镑，则年折旧为（10,000 - 1,000） / 5 = 1,800英镑。
Value = Cost - Accumulated Depreciation. After 2 years, accumulated depreciation would be £3,600, giving a net book value of £6,400.
账面净值 = 成本 - 累计折旧。使用2年后，累计折旧为3,600英镑，账面净值即为6,400英镑。
11. Inventory Valuation: FIFO and Weighted Average Cost | 存货计价：先进先出法与加权平均成本法
When inventory items are bought at different prices, we must determine which cost to assign to cost of sales and closing inventory. Two common methods are FIFO and AVCO.
当存货以不同价格购入时，我们需要确定应将哪部分成本计入销售成本和期末存货。常见的方法有两种：先进先出法（FIFO）和加权平均成本法（AVCO）。
FIFO (First In, First Out) assumes the oldest inventory is sold first. Closing inventory is therefore valued at the most recent purchase costs. In periods of rising prices, FIFO gives a higher closing inventory value.
先进先出法假定最先购入的存货最先售出，因此期末存货按最近购入的成本计价。在物价上涨时期，FIFO会得出较高的期末存货价值。
eighted Average Cost per Unit = Total Cost of Inventory Available / Total Units Available.
加权平均成本法在每次采购后重新计算单位平均成本。公式：每单位加权平均成本 = 可供销售存货的总成本 / 可供销售的总单位数。
For example, 10 units at £2, then 10 units at £3. Total cost is £50 for 20 units, average £2.50. If 12 units are sold, cost of sales is 12 × £2.50 = £30 under AVCO.
例如，先按2英镑购入10单位，再按3英镑购入10单位。总成本50英镑，共20单位，平均成本为2.50英镑。若售出12单位，采用AVCO时销售成本为12 × 2.50 = 30英镑。
12. Owner's Equity and Drawings | 所有者权益与提款
Owner's equity changes with capital introduced, net profit earned, and drawings taken out by the owner. A simple equation summarises the movement.
所有者权益随投入的资本、赚取的净利润和业主提款而变动。一个简明的等式可以概括这一变化。
y = Opening Equity + Capital Introduced + Net Profit - Drawings. Drawings reduce the owner's claim on the business assets.
期末权益 = 期初权益 + 投入资本 + 净利润 - 提款。提款减少所有者对企业资产的要求权。
If opening equity is £15,000, additional capital £2,000, net profit £5,000 and drawings £3,000, closing equity is £19,000. This matches the accounting equation on the balance sheet.
若期初权益15,000英镑，追加资本2,000英镑，净利润5,000英镑，提款3,000英镑，则期末权益为19,000英镑。这与资产负债表中的会计等式相符。
Tracking this helps ensure that the business records accurately reflect every transaction that affects the owner's stake.
跟踪此项有助于确保企业记录准确反映每一笔影响所有者权益的交易。
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