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ESO Y1 · Mathematics
Numbers · Fractions

The set of rational numbers

$-5$, $\frac{3}{7}$, $8$, $1{,}25$... which family does each of them belong to? All the numbers that you can write as a fraction form the largest set you will use this year: the rational numbers.

The set $\mathbb{Q}$

Venn diagram with three nested ovals showing that the natural numbers are included in the integers and these in the rational numbers, with examples of numbers in each region. ℕ ℤ ℚ 3/7, 1,25, −2/3... −5, −12... 8, 0...
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In a pizzeria, a family pizza has been divided into $8$ identical slices. If Marcos ate $3$ slices, express the part of the pizza he consumed as a fraction and clearly…

In a pizzeria, a family pizza has been divided into $8$ identical slices. If Marcos ate $3$ slices, express the part of the pizza he consumed as a fraction and clearly identify which is the numerator and which is the denominator. How is this fraction read?

Solve
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Write the following natural numbers as fractions (you can use any denominator you prefer, as long as the result is correct): a) $3$ b) $1$ c) $5$ d) $10$

Write the following natural numbers as fractions (you can use any denominator you prefer, as long as the result is correct):

  1. a) $3$
  1. b) $1$
  1. c) $5$
  1. d) $10$
Solve
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In mathematics, numbers are organised into "families" or sets. Look at the following Venn diagram representing the sets of Natural numbers ($\mathbb{N}$), Integers…

In mathematics, numbers are organised into "families" or sets. Look at the following Venn diagram representing the sets of Natural numbers ($\mathbb{N}$), Integers ($\mathbb{Z}$), and Rational numbers ($\mathbb{Q}$).

Place each of the following numbers in its corresponding place inside the diagram:

$-5$, $\frac{12}{4}$, $\frac{3}{7}$, $0$, $-\frac{10}{2}$, $1.25$, $-\frac{1}{4}$, $8$

ℚ (Rational numbers) ℤ (Integers) ℕ (Natural numbers)
Solve

Rational numbers on the number line

Every rational number has its exact place on the number line: you divide the section between two integers into as many parts as the denominator says.

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Copy the number line from the figure into your notebook (with 0, 1 and 2, and each unit divided into 4 equal parts) and place the following rational numbers on it:…

Copy the number line from the figure into your notebook (with 0, 1 and 2, and each unit divided into 4 equal parts) and place the following rational numbers on it:

$A = \dfrac{1}{2}$

$B = \dfrac{3}{4}$

$C = \dfrac{5}{4}$

Number line with 0, 1 and 2 marked and each unit divided into four equal parts012

You can do it on paper and send a photo with your answer.

Solve
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Plot on the following number line the points $A$, $B$, $C$ and $D$ that correspond to these rational numbers. Each unit is divided into 4 equal parts. $A = \frac{3}{2}$…

Plot on the following number line the points $A$, $B$, $C$ and $D$ that correspond to these rational numbers. Each unit is divided into 4 equal parts.

$A = \frac{3}{2}$

$B = -1,25$

$C = -\frac{1}{4}$

$D = \frac{11}{4}$

Number line with the integers from −2 to 3, each unit divided into four equal parts, with no points marked−2−10123
Solve

Fractions that give terminating or recurring decimals

Every fraction, when you divide, gives a decimal: sometimes it ends (terminating) and sometimes it repeats for ever (recurring). You can tell without dividing, by looking at the denominator once simplified.

Visual diagram that classifies irreducible fractions into terminating or recurring decimals depending on whether the prime factors of the denominator are only 2 and 5 or include other ones. 7/20 20 = 2² · 5 terminating: 0,35 2/9 9 = 3² recurring: 0,222...
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Identify which of the following fractions will result in a terminating decimal and which in a recurring decimal (pure or mixed) without carrying out the division,…

Identify which of the following fractions will result in a terminating decimal and which in a recurring decimal (pure or mixed) without carrying out the division, looking only at the prime factorisation of their denominators:

  1. a) $\frac{7}{20}$
  2. b) $\frac{5}{12}$
  3. c) $\frac{11}{25}$
  4. d) $\frac{2}{9}$

(Hint: Remember the rule about prime factors 2 and 5 in the denominator).

Solve

Comparing fractions and decimals together

Sometimes you have to compare fractions and decimals at the same time: the safest way is to convert everything to the same form.

Number line between 6,3 and 6,6 showing the ordered comparison of the numbers 6,35, 6,4 and 13/2. 6,3 6,4 6,5 6,6 6,35 6,4 13/2 = 6,5 6,35 < 6,4 < 13/2
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Three friends are completing the "Battle Pass" of their favourite video game. Each has progressed a different fraction of the total: Marcos: has completed…

Three friends are completing the "Battle Pass" of their favourite video game. Each has progressed a different fraction of the total:

  • Marcos: has completed $\frac{12}{18}$ of the total.

  • Sara: has completed $\frac{20}{30}$ of the total.

  • Álex: has completed $\frac{2}{3}$ of the total.

Work out whether the three friends are on the same level of the game by finding the irreducible fraction of each one.

Solve
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In a jumping competition, the judges record the distances of four athletes. Some results are given as fractions and others as decimals: Athlete 1: $6,4$ meters. Athlete…

In a jumping competition, the judges record the distances of four athletes. Some results are given as fractions and others as decimals:

  • Athlete 1: $6,4$ meters.

  • Athlete 2: $\frac{13}{2}$ meters.

  • Athlete 3: $6,35$ meters.

  • Athlete 4: $\frac{32}{5}$ meters.

  1. a) Convert all the measurements to decimal form.
  1. b) Which two athletes jumped exactly the same distance?
  1. c) Order the athletes from the one who jumped the least to the one who jumped the most (if there is a tie, point it out).
Solve

Back to the start: $8$ is natural, an integer and rational; $-5$ is an integer and rational; and $\frac{3}{7}$ and $1{,}25$ are rational (but neither integers nor natural numbers).

Summary

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