In the world of 11+ Maths, no topic is more fundamental than Fractions, Decimals, and Percentages (FDP). These three concepts are the bedrock of numerical reasoning, and a huge number of questions—from word problems to data handling—rely on a child’s ability to understand and manipulate them with ease.
For many children, FDP can feel like learning three different languages. But the secret to mastering them is to realise they are not separate topics at all. They are simply three different ways of saying the exact same thing: a part of a whole.
A child who is fluent in the language of FDP has a huge advantage in the exam. They can solve problems faster, spot connections more easily, and work with greater confidence and accuracy.
At elevenplus.com, we specialise in making complex concepts simple. This guide will demystify FDP, show you the essential facts your child must know by heart, and provide clear methods for any calculation.
In this definitive guide, you will learn:
- A simple explanation of what Fractions, Decimals, and Percentages are.
- The “must-know” FDP conversions that are a superpower for exam speed.
- Simple, step-by-step methods for converting any FDP value.
- How to tackle the most common types of FDP exam questions.
What Are They? Three Ways of Saying the Same Thing
Imagine you have a pizza cut into 10 slices and you eat two of them. You could describe how much you ate in three ways:
- As a Fraction: You ate 2 out of the 10 slices, so you ate 2/10 (which simplifies to 1/5) of the pizza.
- As a Decimal: You ate 0.2 of the pizza.
- As a Percentage: You ate 20% of the pizza.
1/5, 0.2, and 20% all represent the exact same amount. Understanding this core idea is the key to unlocking the entire topic.
The “Must-Know” Conversions: Your Exam Superpower
In the 11+ exam, speed is crucial. A child who can instantly recognise that 3/4 is the same as 0.75 and 75% saves precious time and mental energy. The following conversions are so common that they should be memorised until they are as automatic as 2+2=4.
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/4 | 0.25 | 25% |
| 3/4 | 0.75 | 75% |
| 1/10 | 0.1 | 10% |
| 1/5 | 0.2 | 20% |
| 1/3 | ~0.333 | ~33.3% |
| 2/3 | ~0.666 | ~66.6% |
| 1/8 | 0.125 | 12.5% |
How to Convert Anything: The Methods
For numbers your child hasn’t memorised, they need a clear method for converting between the different forms.
Fraction to Decimal
- The Method: Divide the numerator (top number) by the denominator (bottom number).
- Example: To convert 3/8, you calculate 3 ÷ 8 = 0.375.
Decimal to Percentage
- The Method: Multiply the decimal by 100 (or simply move the decimal point two places to the right).
- Example: To convert 0.65 to a percentage, you calculate 0.65 x 100 = 65%.
Percentage to Fraction
- The Method: Put the percentage number over 100 and then simplify the fraction if possible.
- Example: To convert 40% to a fraction, you write it as 40/100. You can then simplify this by dividing the top and bottom by 20, which gives you 2/5.
[Image: A clear, circular diagram showing arrows connecting “Fraction,” “Decimal,” and “Percentage,” with the conversion methods written alongside each arrow.]
Tackling 11+ FDP Problems
Your child will face two main types of FDP questions.
1. Finding a Fraction or Percentage of an Amount
- Question: “What is 40% of 300?”
- The Method: The easiest way is often to find 10% first. 10% of 300 is 30 (300 ÷ 10). Since 40% is four times bigger than 10%, you just multiply your answer by 4. So, 30 x 4 = 120.
2. Ordering FDPs
- Question: “Put the following in order from smallest to largest: 0.65, 3/5, 62%”
- The Method: The only way to compare them accurately is to convert them all into the same format. Percentages are often the easiest.
- 0.65 = 65%
- 3/5 = 60% (because 1/5 is 20%)
- 62% = 62%
- The Answer: Now it’s easy to see the correct order: 3/5, 62%, 0.65.
From Confusing to Confident
Fractions, Decimals, and Percentages are not as scary as they seem. They are a foundational part of the 11+ Maths curriculum that, with consistent practice, any child can master. By memorising the key facts and learning the core methods, you can empower your child to tackle these questions with speed, accuracy, and confidence.
Ready to put these FDP skills to the test?
➡️ Our elevenplus.com platform includes targeted “Topic Blast” quizzes on every aspect of FDP, from simple conversions to complex word problems, allowing your child to build mastery in a fun and engaging way.
