Introduction to Fractions

Q: What are the numerator and denominator of a fraction?

The numerator is the top number of a fraction, and the denominator is the bottom number. The denominator tells you how many equal parts the whole is divided into. The numerator tells you how many of those parts you are counting. They sit either side of a horizontal bar.

Q: How do you find a fraction of an amount?

To find a fraction of an amount, divide the amount by the denominator. This gives the size of one equal part. Then multiply that part by the numerator. For three quarters of 20 cm, 20 ÷ 4 = 5 cm, then 3 × 5 = 15 cm.

Q: How do you find a fraction of a measurement like 2 hours?

First convert the measurement into smaller units so it divides evenly. For five sixths of 2 hours, change 2 hours into 120 minutes. Divide 120 by the denominator 6 to get 20 minutes for one part. Then multiply by the numerator 5 to reach 100 minutes.

Key concept

Fractions show part of a whole split into equal parts, like a pizza cut into 9 equal slices where taking 4 gives 4/9. The numerator (4) counts the parts taken; the denominator (9) counts the total equal parts.

Introduction to Fractions - introduction visual

Video Lesson

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$Introduction to Fractions poster$

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Flashcards

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$Explanation of fractions with a pizza divided into eight slices, illustrating one-eighth and three-eighths fractions.$ $Explanation of fractions with numerators and denominators, showing a pizza divided into eight equal parts.$ $Understanding fractions with examples, showing 4 out of 9 coloured parts in a circle and an unequally divided rectangle.$ $Applying fractions to real-world examples, including finding 3/4 of 20 cm using a ruler and 5/6 of 2 hours using a clock.$ $Splitting £50 using fractions: the calculation shows it is divided into 10 parts, 1 part = £5, your share = 3 parts, total = £15.$

What is a Fraction?

A fraction shows part of a whole.
For example, if a pizza is cut into 8 equal slices and you take 3, the fraction is 3/8.

Practice Questions

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Q1Easy

In a fraction, what does the denominator tell us?

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Interactive Activity

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Select 1/2 of the pizza

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Students Also Ask

The questions students bump into most on this topic

What are the numerator and denominator of a fraction?

The numerator is the top number of a fraction, and the denominator is the bottom number. The denominator tells you how many equal parts the whole is divided into. The numerator tells you how many of those parts you are counting. They sit either side of a horizontal bar.

Why do the parts of a fraction need to be equal?

The parts must be equal because a fraction only makes sense when the whole is split into equal portions. If a shape is divided into unequal pieces, you cannot tell what fraction it shows. A rectangle with different sized sections would need more information. Equal is the key word.

What does it mean when the numerator is the same as the denominator?

When the numerator equals the denominator, the fraction represents one whole. Every equal part of the whole is being counted, so nothing is left out. For example, a pizza is cut into 8 slices. If you eat all 8, you have eaten eight eighths, the whole pizza.

How do you find a fraction of an amount?

To find a fraction of an amount, divide the amount by the denominator. This gives the size of one equal part. Then multiply that part by the numerator. For three quarters of 20 cm, 20 ÷ 4 = 5 cm, then 3 × 5 = 15 cm.

How do you find a fraction of a measurement like 2 hours?

First convert the measurement into smaller units so it divides evenly. For five sixths of 2 hours, change 2 hours into 120 minutes. Divide 120 by the denominator 6 to get 20 minutes for one part. Then multiply by the numerator 5 to reach 100 minutes.

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