Representation of Rational Numbers on the Number Line

In representation of rational numbers on the number line are discussed here. We know how to represent integers on the number line.To represent the integers on the number line, we need to draw a line and take a point O on it. Call it 0 (zero).

Set of equal distances on the right as well as on the left of O. Such a distance is known as a unit length. Let A, B, C, D, etc. be the points of division on the right of 'O' and A',B', C', D', etc. be the points of division on the left of 'O'. If we take OA = 1 unit, then clearly, the point A, B, C, D, etc. represent the integers 1, 2, 3, 4, etc. respectively and the point A', B', C', D', etc. represent the integers -1, -2, -3, -4, etc. respectively.

Note: The point O represents integer 0.

Representation of Rational Numbers on the Number Line

Thus, we may represent any integer by a point on the number line. Clearly, every positive integer lies to the right of O and every negative integer lies to the left of O.

We can represent rational numbers on the number line in the same way as we have learnt to represent integers on the number line.
In order to represent rational numbers on the number line, first we need to draw a straight line and mark a point O on it to represent the rational number zero. The positive (+ve) rational numbers will be represented by points on the number line lying to the right side of O and negative (-ve) rational numbers.

If we mark a point A on the line to the right of  O  to represent 1, then OA = 1 unit. Similarly, if we choose a point A' on the line to the left of O to represent -1, then OA' = 1 unit.

Consider the following examples on representation of rational numbers on the number line;

1. Represent \(\frac{1}{2}\) and \(\frac{-1}{2}\) on the number line.

Solution:


Draw a line. Take a point O on it. Let the point O represent 0. Set off unit lengths OA to the right side of O and OA' to the left side of O.

Then, A represents the integer 1 and A' represents the integer -1.

Represent 1/2 and -1/2 on the number line

Now, divide the segment OA into two equal parts. Let P be the mid-point of segment OA and OP be the first part out of these two parts. Thus, OP = PA = \(\frac{1}{2}\). Since, O represents 0 and A represents 1, therefore P represents the rational number \(\frac{1}{2}\).

Again, divide OA' into two equal parts. Let OP' be the first part out of these two parts. Thus, OP' = PA' = \(\frac{-1}{2}\). Since, O represents 0 and A' represents -1, therefore P' represents the rational number \(\frac{-1}{2}\).



2. Represent \(\frac{2}{3}\) and \(\frac{-2}{3}\) on the number line.

Solution:


Draw a line. Take a point O on it. Let it represent 0. From the point O set off unit distances OA to the right side of O and OA'  to the left side of O respectively.

Divide OA into three equal parts. Let OP be the segment showing 2 parts out of 3. Then the point P represents the rational number \(\frac{2}{3}\).

Represent 2/3 and -2/3 on the number line

Again, divide OA' into three equal parts. Let OP' be the segment consisting of 2 parts out of these 3 parts. Then, the point P' represents the rational number \(\frac{-2}{3}\).



3. Represent \(\frac{13}{5}\) and \(\frac{-13}{5}\) on the number line.

Solution:


Draw a line. Take a point O on it. Let it represent 0.

Now, \(\frac{13}{5}\) = 2\(\frac{3}{5}\) = 2 + \(\frac{3}{5}\)

From O, set off unit distances OA, AB and BC to the right of O. Clearly, the points A, B and C represent the integers 1, 2 and 3 respectively. Now, take 2 units OA and AB, and divide the third unit BC into 5 equal parts. Take 3 parts out of these 5 parts to reach at a point P. Then the point P represents the rational number \(\frac{13}{5}\).

Represent 13/5 and -13/5 on the number line

Again, from the point O, set off unit distances to the left. Let these segments be OA', A' B', B’ C’, etc. Then, clearly the points A’, B’ and C’ represent the integers -1, -2, -3 respectively.

Now, = -\(\frac{13}{5}\) = -(2 + \(\frac{3}{5}\))

Take 2 full unit lengths to the left of O. Divide the third unit B’ C’ into 5 equal parts. Take 3 parts out of these 5 parts to reach a point P’.

Then, the point P’ represents the rational number -\(\frac{13}{5}\).

Thus, we can represent every rational number by a point on the number line.

Rational Numbers

Introduction of Rational Numbers

What is Rational Numbers?

Is Every Rational Number a Natural Number?

Is Zero a Rational Number?

Is Every Rational Number an Integer?

Is Every Rational Number a Fraction?

Positive Rational Number

Negative Rational Number

Equivalent Rational Numbers

Equivalent form of Rational Numbers

Rational Number in Different Forms

Properties of Rational Numbers

Lowest form of a Rational Number

Standard form of a Rational Number

Equality of Rational Numbers using Standard Form

Equality of Rational Numbers with Common Denominator

Equality of Rational Numbers using Cross Multiplication

Comparison of Rational Numbers

Rational Numbers in Ascending Order

Rational Numbers in Descending Order

Representation of Rational Numbers on the Number Line

Rational Numbers on the Number Line

Addition of Rational Number with Same Denominator

Addition of Rational Number with Different Denominator

Addition of Rational Numbers

Properties of Addition of Rational Numbers

Subtraction of Rational Number with Same Denominator

Subtraction of Rational Number with Different Denominator

Subtraction of Rational Numbers

Properties of Subtraction of Rational Numbers

Rational Expressions Involving Addition and Subtraction

Simplify Rational Expressions Involving the Sum or Difference

Multiplication of Rational Numbers

Product of Rational Numbers

Properties of Multiplication of Rational Numbers

Rational Expressions Involving Addition, Subtraction and Multiplication

Reciprocal of a Rational  Number

Division of Rational Numbers

Rational Expressions Involving Division

Properties of Division of Rational Numbers

Rational Numbers between Two Rational Numbers

To Find Rational Numbers







8th Grade Math Practice

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