Mastering Everyday Calculations
Mastering Everyday Calculations
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Mastering Everyday Calculations
What do you already know about calculating with decimals and fractions?
Learning Objective
At the end of the lesson you will be able to calculate with fractions, decimals and percentages, round numbers correctly, estimate, and solve practical problems using your calculator.
What is a Square Number?
A square number is a number multiplied by itself. For example, 3 × 3 = 9, so 9 is a square number.
Examples of Square Numbers
2 × 2 = 4 (written as 2² = 4). 3 × 3 = 9 (written as 3² = 9).
Rounding Decimal Numbers
We round decimal numbers to make them easier to work with. You can round to the nearest whole number, tenth, or hundredth.
How to Round to the Nearest Whole Number
Look at the tenths digit (one place after the decimal). If it is 5 or more, round up. If it is less than 5, leave it as it is.
Using Estimation in Calculations
Rounding to the Nearest Tenth and Hundredth
To round to the nearest tenth, check the hundredths place. For the nearest hundredth, check the thousandths place. Round up if 5 or more; otherwise, keep the digit the same.
Converting Pounds and Pence
There are 100 pence in £1. For example, £2.05 is the same as 205p.
Adding and Subtracting Decimals
Line up the decimal points and subtract each column.
Line up the decimal points and add each column.
Subtracting Decimals
Adding Decimals
Calculator Tips
When using calculators, enter numbers carefully and check your answer makes sense with an estimation.
Understanding Fractions
Using Fractions in Practical Problems
To find a fraction of a quantity, divide by the denominator, then multiply by the numerator.
Percentages: Quick Guide
Percentages are parts per hundred. To find a percentage of a number, multiply the number by the percentage and divide by 100.
Rounding with Money
When rounding money to the nearest 10p or £, follow the same rounding rules as decimals.
Checking Your Answers
Always estimate your answer before checking with a calculator. Ask: does my answer look sensible?
Ordering Decimals
Add zeros if needed to make comparing easier (e.g. 3.2 = 3.20).
Start with the largest digit and move to the right to compare numbers.
Top Tip
Compare Place Values
Key Words to Remember
Square number, decimal place, tenths, hundredths, rounding, estimation, calculator, fraction, percentage.
Practise Your Skills
Test Your Understanding
Money Example
Round 7.6 to the nearest whole number.
Rounding Example
What is £3.50 in pence?
Real-Life Problem Solving
A ticket costs £12.00. With a half-price discount, how much is the discount?
Summary
You can now round decimals, add and subtract decimals, estimate, use fractions and percentages, and solve real-life calculation problems!
Write down 3 things you learned in this lesson.
Write down 2 things you want to know more about.
Ask 1 question about something you haven't quite understood yet.
