Maths for life means the handful of practical calculations adults use every week: working out percentages and discounts, comparing unit prices, budgeting, estimating time and cost, and understanding how interest makes savings grow and debt more expensive. You do not need advanced algebra. Confidence with percentages, ratios, simple multiplication and a few formulas covers most of what everyday life throws at you, and this guide shows each one with worked UK examples.
| Skill | Where you use it | Quick method |
| Percentages | Sales, pay rises, tips, VAT | 10% = divide by 10; build other percentages from it |
| Unit pricing | Supermarket shopping | Price ÷ quantity, then compare like with like |
| Budgeting | Monthly bills, groceries | Income − fixed costs − savings = spending money |
| Rates | Energy use, fuel, travel time | Amount per unit × number of units |
| Compound interest | Savings, loans, credit cards | A = P(1 + r/n)nt |
Why everyday maths matters
Many adults in the UK say they feel anxious about numbers, and organisations such as National Numeracy campaign to change that. The good news is that the maths that saves money and time is learnable in small pieces. The aim is not to do everything in your head, but to know which calculation to do, roughly what the answer should be, and when a deal or offer does not add up.
Smart shopping with maths
Working out discounts quickly
The formula is: final price = original price − (original price × discount rate). A £80 jacket at 25% off costs £80 − £20 = £60. A faster mental route is to multiply by what you actually pay: 25% off means you pay 75%, so £80 × 0.75 = £60.
For awkward percentages, start from 10%. To find 35% of £46: 10% is £4.60, so 30% is £13.80, 5% is £2.30, and 35% is £16.10. The same trick works for adding a 20% VAT charge to a business quote or estimating a 12.5% service charge on a restaurant bill.
Stacked discounts are not added together
“20% off, plus an extra 10% at the till” is not 30% off. The second discount applies to the already reduced price: £100 becomes £80, then £72. That is a 28% saving overall. Knowing this stops you overestimating how good a promotion is.
Comparing unit prices
Bigger packs are usually, but not always, cheaper per unit. UK supermarkets generally show a unit price on shelf labels, such as per kg, per 100g, per litre or per 100 sheets, which does the division for you. Check that both products use the same unit before comparing, because one label may say per kg and another per 100g.
If you need to do it yourself, divide price by quantity. A 500g bag of pasta at £0.90 costs 18p per 100g. A 1kg bag at £1.60 costs 16p per 100g, so the larger bag is cheaper, as long as you will use it before it goes stale. Multi-buy offers work the same way: “3 for £5” on items that are £1.60 each is actually more expensive than buying three singly at £4.80.
Budgeting for groceries
- Track for four weeks: keep receipts or check your banking app and total your food spending.
- Find the weekly average: divide the four-week total by four. If you spent £340, that is £85 a week.
- Set a target: trimming 10% gives a £76.50 target, a realistic first step.
- Keep a running total: round each item up to the nearest pound as it goes in the trolley. Rounding up builds in a buffer.
- Review monthly: if you consistently go over or under, adjust the target rather than abandoning the budget.
Maths in the home
Energy costs
Appliances are rated in watts, and you pay for electricity per kilowatt-hour (kWh). The calculation is: watts × hours ÷ 1,000 = kWh, then kWh × your unit rate = cost. A 2,000W heater used for 3 hours uses 6kWh. If your unit rate were 25p per kWh, that would cost £1.50. Your actual unit rate is on your bill or supplier app, and it changes with price cap updates, so plug in your own figure.
Measuring for DIY
Area is length × width. A room of 4m × 3.5m is 14 square metres. For flooring or paint, add around 10% for waste and cutting, so buy for about 15.4 square metres. For paint, check the coverage per litre on the tin and divide the wall area by it, remembering to multiply by the number of coats.
Problem-solving skills for real life
The biggest benefit of maths is not a particular formula but a way of thinking: break a problem into parts, put numbers on each part, and compare options fairly. Here is a simple framework using a real decision, whether to buy a car or keep using public transport.
- Define the question: “What is the cheapest reliable way to get to work for the next three years?”
- List every cost: for the car, purchase or finance payments, insurance, vehicle tax, MOT, servicing, fuel and parking. For transport, season tickets and occasional taxis.
- Put costs on the same time scale: convert everything to a monthly or annual figure. Annual insurance of £600 is £50 a month.
- Compare totals and non-money factors: journey time, flexibility and reliability matter too.
- Decide, then review: check after a few months whether the real costs matched your estimates.
The same approach works for choosing a phone contract (monthly cost × contract length + upfront fee), planning a holiday, or dividing a shared bill fairly by using ratios rather than splitting evenly.
Estimation: the underrated skill
Rounding numbers before calculating lets you sense-check answers. If a receipt for eight items that all cost around £2 comes to £31, something is wrong. Estimation also helps with time: a 180-mile drive at an average of 50mph is about three and a half hours before breaks and traffic.
Maths for future planning
Setting a savings goal
A useful goal is specific and time-bound: “save £3,000 for a deposit on a car in 18 months”. Divide the target by the months: £3,000 ÷ 18 is about £167 a month. If that is too much, you can extend the deadline or reduce the target, and the maths shows the trade-off instantly.
How compound interest works
Compound interest means you earn interest on your interest. The formula is A = P(1 + r/n)nt, where A is the final amount, P the starting sum, r the annual rate as a decimal, n the number of times interest is added each year, and t the number of years.
Example: £1,000 at 5% compounded once a year for 10 years gives £1,000 × 1.0510, which is about £1,628.89. With simple interest you would have only £1,500. A handy shortcut is the rule of 72: divide 72 by the interest rate to estimate how many years it takes money to double. At 6%, that is roughly 12 years.
The same maths works against you on debt. Credit cards and loans quote an APR, while savings accounts quote an AER; both are designed to let you compare products fairly over a year. If you are weighing up borrowing, a tool such as our guide to the Tesco loan calculator shows how the rate and term change what you repay in total. Rates also move with the Bank of England base rate, which we cover in our UK interest rate predictions article.
Fees matter more than they look
A small annual fee on investments compounds too. Compare two funds growing at the same rate where one charges 0.2% a year and the other 1%: over decades the gap in the final pot can be large, because the fee is taken from a growing balance every year. Our explainer on Vanguard fees walks through how platform and fund charges add up.
Planning for retirement
- Estimate spending: start with your current annual costs, then adjust for things that change, such as mortgage payments ending.
- Identify income sources: the State Pension (you can get a forecast on GOV.UK), workplace pensions and personal savings.
- Find the gap: spending minus expected income shows what your own savings need to cover.
- Use the employer match: under auto-enrolment, the legal minimum total contribution is generally 8% of qualifying earnings, with at least 3% from the employer. Contributing enough to get any extra matching is often the best return available.
Maths in everyday digital life
Subscriptions are a classic place where small numbers hide big totals. Five subscriptions at £8.99 a month add up to nearly £540 a year. Multiplying monthly costs by 12 is one of the simplest and most effective money checks you can do. Mobile data works the same way: if you use about 6GB a month, paying for an unlimited plan may cost more than you need.
Reading charts and percentages in the news is part of maths for life too. A “50% increase” in a very rare risk may still be a tiny risk, and an average can hide wide variation. Asking “50% of what?” is a habit worth building.
How to build confidence with numbers
- Estimate the total before you reach the till, then compare with the receipt.
- Work out percentages from 10% rather than reaching for your phone every time.
- Involve children in real calculations such as recipe scaling, change and journey times.
- Use free adult numeracy courses; many local councils and colleges offer them, and National Numeracy has free online tools.
For more learning guides, explore our Education category.
Frequently asked questions
What is maths for life?
It is the practical maths adults use daily, such as percentages, unit prices, budgeting, measuring and interest. The name is also used by some school programmes that focus on functional maths skills.
How do I work out a percentage discount in my head?
Find 10% by dividing by 10, then build up. For 30% off £50, 10% is £5, so 30% is £15 and you pay £35.
Is a bigger pack always cheaper?
No. Check the unit price on the shelf label, such as price per kg or per 100g, and make sure both products use the same unit before comparing.
What is the rule of 72?
Divide 72 by an annual interest rate to estimate how many years it takes money to double. At 6% it takes about 12 years.
How do I calculate what an appliance costs to run?
Multiply watts by hours used and divide by 1,000 to get kWh, then multiply by your electricity unit rate from your bill.
This article is general information, not financial advice.
