Money Sums

Use this when someone running a business gives their fixed costs for a period (rent, wages, power for a month), what one item costs them and what they sell it for, and asks how many they must sell to cover their costs (break even). Do not use it for a business plan's forecasts or to judge whether a business will succeed.

Use this when a trader gives what an item costs them and either what they sell it for, the margin they want, or the markup they want, and asks for the profit, the margin, the markup or what to sell it for (for example "I buy a bag of rice for 800 and want a 20% margin"). It keeps margin (a share of the sale) and markup (a share of the cost) apart, which are often confused. Do not use it for tax on a sale (use a VAT tool), for exchange rates, or to suggest what the market will pay.

Use this when someone gives a loan amount, an interest rate and a number of weekly, fortnightly or monthly repayments, and asks what each repayment is, what the loan costs in total, or what the rate really is a year, for example "a microfinance loan of 5,000 at 5% flat a month for 6 months". It handles a flat rate (interest on the whole amount for the whole term, common with microfinance and hire purchase) and a reducing-balance rate, and fees taken at the start. Do not use it for a loan repaid in one sum (use loan.one_repayment), for a mortgage with a changing rate, or to say whether a loan is a good idea.

Use this when someone borrows an amount and repays a single larger sum after some days, as with a phone or app loan, a salary advance or a loan from a moneylender, and asks what rate that is a month or a year (for example "I borrowed 1,000 and must repay 1,150 in 30 days"). Do not use it for a loan repaid in instalments (use loan.instalments), and do not use it to judge a lender.

Use this when someone saves with a collector who takes regular deposits and keeps some of them as a fee (susu in Ghana, ajo or esusu in Nigeria, a daily contribution card), and asks how much they get back, what the fee is, or what it costs as a rate. A common arrangement is a daily deposit for 31 days with one day's deposit kept as the fee. Do not use it for a rotating group where members take turns to collect (a chama or rotating susu), for a bank savings account, or to judge a collector.