Chapter 1: Number skills

By the end of this chapter

You will be able to:

• read, write and order numbers, including decimals and negative numbers;
• add, subtract, multiply and divide with integers and decimals using reliable written methods;
• work with negative numbers in context, including profit and loss;
• use the correct order of operations and check a calculation with an inverse operation;
• round to a required degree of accuracy, estimate, and use estimation to check an answer.

The chapter problem: the school-fair stall

You are running the drinks-and-cakes stall at the school fair. The cash box starts with a £50 float — money you must give back at the end.

• You buy 120 cans of drink at 65p each.
• You buy 8 boxes of cakes at £1.85 each.
• You sell 95 cans at £1.20 each.
• You sell 6 boxes of cakes at £3.00 each.

By the end of the chapter you will work out exactly whether the stall made a profit or a loss, how much, and how much money should be in the cash box.

First contact — no working yet. Before any exact calculation, estimate. Do you expect a profit or a loss? Roughly how much?

Where it is used

Cash handling, budgets, profit and loss, and estimating before you commit money. The same skills underpin wages, bills, savings and unit pricing in a shop.

Your turn to connect it

Where in your own week do you meet negative numbers, or need a quick estimate before deciding something? Write two examples: one about money, and one that is not about money.

How to use this chapter

Each section has three parts:

The Review page resolves the chapter problem and mixes the chapter's methods together. Round numbers, do not memorise them: if a step is unclear, the worked example above it will show the reasoning.

Roadmap

1. 1.1 Place value and ordering numbers
2. 1.2 The four operations
3. 1.3 Negative numbers
4. 1.4 Priority of operations and inverse operations
5. 1.5 Rounding and estimation
6. Review