📚 Year 9 SQA Accounting: Quick-Reference Formula & Theorem Handbook | Year 9 SQA 会计：公式定理速查手册
This handbook brings together the essential formulas and underlying theorems you need to master in the SQA Accounting course at Year 9 level. Each entry is designed to help you memorise core calculations, understand their logic, and apply them confidently to numerical problems and final accounts. Keep this guide close for revision, homework, and exam preparation.
本手册汇集了 Year 9 SQA 会计课程中必须掌握的关键公式与基础定理。每一个条目都旨在帮助你记住核心计算、理解其内在逻辑，并能在做计算题和编制最终报表时自信地运用。平时复习、写作业和备考时，请随时查阅这份速查指南。
1. The Accounting Equation | 会计恒等式
The most fundamental formula in accounting states that the resources of a business are always equal to the claims against those resources. This equation must remain balanced after every transaction, and it underpins the entire double‑entry system.
会计中最基本的公式表明：企业的资源永远等于对这些资源的要求权。每笔交易发生后该等式都必须保持平衡，它是整个复式记账体系的基石。
Assets = Liabilities + Owner’s Equity
资产 = 负债 + 所有者权益
Assets include everything the business owns or controls, such as cash, inventory, and premises. Liabilities represent amounts owed to third parties, like bank loans and trade payables. Owner’s equity is the residual interest after deducting liabilities from assets – often called capital. When a business makes a profit, equity increases; when it incurs a loss or the owner makes drawings, equity decreases.
资产包括企业拥有或控制的一切资源，例如现金、存货和房产。负债代表欠第三方的款项，如银行贷款和应付账款。所有者权益是资产扣除负债后的剩余利益——通常称为资本。当企业实现利润时，权益增加；发生亏损或所有者提款时，权益减少。
2. The Double-Entry Principle | 复式记账原则
This theorem is the mechanical heart of accounting. Every transaction affects at least two ledger accounts – one debit entry and one credit entry – and total debits must always equal total credits. The golden rules for double entry are based on the accounting equation and the nature of the account.
该定理是会计的机械核心。每笔交易至少影响两个分类账户——一笔借方分录和一笔贷方分录——并且借方总额必须始终等于贷方总额。复式记账的黄金法则基于会计恒等式和账户的性质。
| Account Type | To Increase | To Decrease |
|---|---|---|
| Asset | Debit | Credit |
| Liability | Credit | Debit |
| Equity (Capital) | Credit | Debit |
| Revenue | Credit | Debit |
| Expense | Debit | Credit |
When a business purchases inventory with cash, the asset ‘Inventory’ is debited, and the asset ‘Cash’ is credited. When it records a credit sale, ‘Trade Receivables’ (asset) is debited, and ‘Sales Revenue’ (revenue) is credited. Memorising these simple rules makes complex journal entries much easier.
当企业用现金购买存货时，资产“存货”借记，资产“现金”贷记。当记录赊销时，“应收账款”（资产）借记，“销售收入”（收入）贷记。记住这些简单规则会让复杂的日记账分录变得容易得多。
3. Profit Calculation | 利润计算
Profit is the reward for business activity and a key measure of performance. The two‑step calculation separates the trading result from the overall net result, allowing you to see both gross profit and net profit clearly.
利润是经营活动带来的回报，也是衡量业绩的关键指标。两步计算将购销结果与整体净结果分开，使你能够清晰地看到毛利和净利。
Gross Profit = Sales Revenue – Cost of Goods Sold
毛利 = 销售收入 – 销售成本
Net Profit = Gross Profit – All Other Expenses
净利 = 毛利 – 所有其他费用
Cost of goods sold is usually found by adding opening inventory to purchases and subtracting closing inventory. Other expenses include rent, wages, advertising, and depreciation. If net profit is positive, the business has earned more than it spent; if negative, it has made a net loss.
销售成本通常通过期初存货加购货减去期末存货来计算。其他费用包括租金、工资、广告费和折旧。如果净利为正，说明企业收入大于支出；如果为负，则出现了净亏损。
4. Gross Profit & Gross Profit Margin | 毛利与毛利率
Gross profit margin expresses gross profit as a percentage of sales revenue, showing how efficiently a business turns its purchases into sales income before deducting overheads. This is a vital profitability ratio from the trading account.
毛利率将毛利表示为销售收入的一个百分比，反映企业在扣减间接费用之前，将购货转化为销售收入的效率。这是来自购销账的一项关键盈利能力比率。
Gross Profit Margin (%) = (Gross Profit ÷ Sales Revenue) × 100
毛利率 (%) = (毛利 ÷ 销售收入) × 100
A margin of 40% means that for every £1 of sales, the business earned 40 pence in gross profit after covering the direct cost of the goods sold. A falling gross margin may signal increasing purchase costs, increasing wastage, or selling goods at lower mark‑ups. Year‑on‑year comparisons help identify trends.
毛利率为 40% 意味着每 1 英镑的销售收入中，企业在覆盖售出商品的直接成本后赚取了 40 便士的毛利。毛利率下降可能预示着采购成本上升、损耗增加或商品加价率降低。逐年对比有助于识别趋势。
5. Net Profit & Net Profit Margin | 净利与净利率
Net profit margin reveals the percentage of sales revenue that remains after all expenses – both direct and indirect – have been deducted. It is the ultimate indicator of a business’s overall profitability and cost control.
净利率揭示了在扣减所有直接和间接费用之后，销售收入中还剩下百分之几。它是衡量企业整体盈利能力和成本控制的终极指标。
Net Profit Margin (%) = (Net Profit ÷ Sales Revenue) × 100
净利率 (%) = (净利 ÷ 销售收入) × 100
For example, a net margin of 15% indicates that 15 pence of every sales pound is available for the owner. If the margin is too low, the business may struggle to reward the owner or reinvest. Analysts compare net margin with the gross margin to see how overheads are eating into trading profits.
例如，15% 的净利率表明每 1 英镑销售额中有 15 便士归所有者所有。如果该比率过低，企业可能难以回报所有者或进行再投资。分析人员会将净利率与毛利率进行比较，以了解间接费用对购销利润的侵蚀程度。
6. Working Capital | 营运资金
Working capital measures the short‑term financial health of a business – its ability to meet day‑to‑day obligations as they fall due. It is not a ratio but a straightforward net figure derived from the statement of financial position.
营运资金衡量企业的短期财务健康状况——即其偿还到期日常债务的能力。它不是一个比率，而是直接取自财务状况表的一个净额数字。
Working Capital = Current Assets – Current Liabilities
营运资金 = 流动资产 – 流动负债
A positive working capital balance suggests that the business can comfortably pay its short‑term debts. A negative figure warns that liabilities falling due within 12 months exceed the assets expected to convert into cash in the same period, potentially leading to cash flow problems.
营运资金为正数表明企业能够轻松偿还短期债务。负数则警示：12 个月内到期的负债超过了同一时期预计能够变现的资产，可能导致现金流问题。
7. Current Ratio | 流动比率
The current ratio (sometimes called the working capital ratio) compares total current assets with total current liabilities. It gives a proportional view of liquidity and is a fundamental health check for the SQA Accounting analysis.
流动比率（有时称为营运资金比率）将流动资产总额与流动负债总额进行比较。它提供了关于流动性的比例视角，是 SQA 会计分析中的一项基本健康检查。
Current Ratio = Current Assets ÷ Current Liabilities
流动比率 = 流动资产 ÷ 流动负债
A ratio of 2.0 : 1 is often cited as a comfortable benchmark, but acceptable levels vary by industry. If the ratio is too high, the business may be holding too much inventory or cash that could be used more productively. A ratio below 1.0 means current liabilities exceed current assets, a clear liquidity risk.
2.0 : 1 的比率常被引作舒适基准，但可接受水平因行业而异。比率过高可能意味着企业持有过多可更有效利用的存货或现金。比率低于 1.0 则意味着流动负债超过流动资产，存在明显的流动性风险。
8. Quick Ratio (Acid Test) | 速动比率 (酸性测试)
The quick ratio refines the current ratio by removing inventory – usually the least liquid current asset – from current assets. It tests whether the business can meet its immediate liabilities using only its most liquid assets.
速动比率通过从流动资产中剔除存货（通常是流动性最差的流动资产）来优化流动比率。它测试企业仅使用最具流动性的资产能否偿还其即期负债。
Quick Ratio = (Current Assets – Inventory) ÷ Current Liabilities
速动比率 = (流动资产 – 存货) ÷ 流动负债
A ratio of 1.0 : 1 or higher is generally considered healthy, as it shows that the business can pay its short‑term debts without relying on selling inventory quickly. A very low quick ratio may signal a reliance on inventory liquidation to stay afloat, which can be dangerous if sales slow down.
1.0 : 1 或更高的比率通常被认为是健康的，因为它表明企业无需依赖快速出售存货即可偿还短期债务。速动比率非常低可能意味着企业依赖存货变现来维持运营，一旦销售放缓就会面临危险。
9. Inventory Turnover | 存货周转率
Inventory turnover measures how many times a business sells and replaces its stock over a given period. It is a crucial efficiency ratio that links the trading account to inventory management.
存货周转率衡量企业在特定时期内售出并重置存货的次数。这是一个关键的效率比率，将购销账与存货管理联系起来。
Inventory Turnover (times) = Cost of Goods Sold ÷ Average Inventory
存货周转率 (次) = 销售成本 ÷ 平均存货
Average inventory is often calculated as (Opening Inventory + Closing Inventory) ÷ 2. A high turnover suggests that goods are selling quickly, reducing the risk of obsolescence. A low turnover may indicate overstocking, poor purchasing decisions, or weak demand.
平均存货通常计算为（期初存货 + 期末存货）÷ 2。高周转率表明商品销售快，降低过时风险。低周转率可能意味着存货积压、采购决策不当或需求疲软。
10. Trade Receivables Collection Period | 应收账款周转天数
This efficiency ratio calculates the average number of days it takes for a business to collect cash from its credit customers. It is a direct measure of how well the business manages its trade receivables.
该效率比率计算企业从赊销客户处收回现金所需的平均天数。它直接衡量企业管理应收账款的优劣程度。
de Receivables Collection Period (days) = (Trade Receivables ÷ Credit Sales Revenue) × 365
应收账款周转天数 (天) = (应收账款 ÷ 赊销收入) × 365
A short collection period indicates an efficient credit control system and prompt cash inflows. An increasing period could mean customers are struggling to pay or that the business is too lenient with credit terms. This formula expects you to use total sales if credit sales are not separately disclosed, a common SQA scenario.
较短的周转天数表明信用控制体系高效，现金流入及时。天数增加可能意味着客户付款困难，或企业信用条款过于宽松。在 SQA 题目中，如果未单独披露赊销额，通常使用销售总额进行计算。
11. Trade Payables Payment Period | 应付账款周转天数
This ratio shows the average number of days a business takes to settle its debts with suppliers. It gives insight into the company’s payment culture and its relationship with the supply chain.
该比率显示企业偿还供应商债务的平均天数。它有助于洞察企业的付款习惯及其与供应链的关系。
Trade Payables Payment Period (days) = (Trade Payables ÷ Credit Purchases) × 365
应付账款周转天数 (天) = (应付账款 ÷ 赊购额) × 365
A longer payment period can help the business conserve cash, but stretching it too far may damage supplier goodwill and lead to lost discounts. A stable period that aligns with industry norms is usually desirable. Again, if credit purchases are unknown, total purchases may be used as a proxy.
较长的付款期有助于企业节省现金，但过长可能损害供应商关系并导致错失折扣。一个与行业规范相符的稳定天数通常是可取的。同样，若赊购额未知，可用总购货额替代。
12. Fundamental Accounting Theorems | 基础会计定理
Several governing concepts, often called accounting principles or theorems, guide the preparation of accounts. They ensure that financial statements are reliable, relevant, and consistent. Three of the most important for Year 9 SQA are the going concern concept, the accruals (matching) concept, and the prudence concept.
若干统御性概念——通常被称为会计原则或定理——指导着报表的编制。它们确保财务报表可靠、相关且一致。Year 9 SQA 课程中最重要的三个是持续经营概念、权责发生制（配比）概念和谨慎性概念。
Going Concern: Accounts are prepared on the assumption that the business will continue to operate for the foreseeable future. This justifies valuing assets at cost rather than break‑up value and spreading depreciation over useful lives.
持续经营： 编制报表时假定企业在可预见的未来将继续经营。这为按成本而非清算价值对资产计价、以及在使用寿命内分摊折旧提供了依据。
Accruals (Matching): Revenue and expenses are recorded in the period they are earned or incurred, regardless of when cash is received or paid. This matches income with the costs incurred to generate it, presenting a true profit for the period.
权责发生制（配比）： 收入和费用在其赚取或发生的期间内记录，而不论现金何时收付。这将收入与为其发生的成本相配比，从而反映出当期的真实利润。
Prudence: Accountants should exercise caution when making estimates, recognising all foreseeable losses and liabilities but never anticipating profits until they are virtually certain. This protects users from overly optimistic statements.
谨慎性： 会计师在作出估计时应保持审慎，确认所有可预见的损失和负债，但绝不预计未基本确定的利润。这保护报表使用者免受过分乐观信息的误导。
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