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Decimal numbers are a form of number in mathematics used in representing a fraction of a number. These numbers lie between two whole numbers. For example, 1.5 will be a decimal number as it lies between two whole numbers 1 and 2.
- For denoting integers and non integers decimal numbers are used.
- In decimal numbers the whole number and the fractional part are separated by a decimal point (.).
- In ancient India Aryabhata and other mathematicians were the first ones to use the decimal system of numbers.
| Table of Content |
Key Terms: Decimal Numbers Whole Number, Fraction, Number Line.
What are Decimal Numbers?
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Decimal numbers are a certain type of number where a decimal point is separating two parts of a number; one of them is an integer and the other one is a fractional part. For example, if 3 biscuits are being divided between 2 kids then each of them will get 1.5 biscuits. Here, 1.5 is a decimal number, where 1 is the integer part and the number after the decimal point is the fractional part.
- To check if a number is logical or irrational decimal numbers are used.
- All decimal numbers are fractions.
- Tenths, hundredths, thousandths, and other fractions of a unit are expressed by decimals.
Read More: Polynomial Equation
How are Decimal Numbers Represented?
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A non-negative real number ‘r’ can be written as a combined form of its whole number and fractional part; the form will look like –
r = \(\sum^k_{i=0} b_i10^i = \sum^{\infty} _{i = 1} \frac{a_i}{10^i}\)
Here, the first part of the equation represents the integer part and the second part of the equation represents the fractional part. Here, ai is a non-negative integer and a1, a2, …are the integers satisfying the condition 0≤ ai≤ 9
Decimal numbers are all rational numbers and there could be two possibilities such as the number might be a terminal decimal number or it can be a repeating decimal number.
For example, ⅖ = 0.4 is an example of terminating decimal number.
And ⅓ = 0.33333…… is an example of repeating decimal number.
A decimal number 11.256 will sound like “eleven point two five six”.

Coloring in one of the squares in the table, will represent decimal 0.01. This means 0.01 is equal to one hundredth (1/100).

This would be represented by 0.1, as 10 boxes are coloured among the 100 and 10/100 = 0.1
Read More: Real-Valued Function
Decimal Number Representation on a Number Line
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Considering a line from 0 to 1 it is possible to get a concept about the position of the decimal numbers on that line.

Now, the distance between these two numbers can be divided into ten parts and the middle point of this number line will be 0.5

For example, the position of 0.7 in the number line will be –

Read More:
| Relevant Concepts | ||
|---|---|---|
| Pair of Linear Equation with 2 variables | Substitution method | Elimination method |
Solved Examples
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Example 1: Represent 4.6 on the number line.
Solution: The number 4.6 = 4 + 0.6
From the number 4.6 on the number line the section between 4 and 5 is divided into 10 equal parts. Now, to represent 4.6 the position should be starting from 4 towards six steps ahead of 5.

Example 2: Represent 0.3 on the number line.
Solution: The number 0.3 = 0 + 0.3
From the number 0.3 on the number line the section between 0 and 1 is divided into 10 equal parts. Now, to represent 0.3 the position should be starting from 0 towards six steps ahead of 1.

Things to Remember
- Decimal number lies between two whole numbers.
- Decimal numbers consist of two parts: the first part is the whole number and the second part is the fraction.
- Both the whole number and fractional part is separated by a decimal point (.).
- All decimal numbers are fractions.
- Decimals express tenths, hundredths, thousandths, and other fractions of a unit.
- To represent any decimal number the distance between two whole numbers can be divided into ten parts.
Sample Questions
Ques: Write the given rational numbers as decimals 3/5 and 1/4. (2 Marks)
Ans: 3/5 = (3 x 2 )/(5 x 2)= 6 /10 = 0.6; The denominator is a multiple of 10 here to make the calculation easier.
1/4 = (1x 25)/(4 x 25)= (25 /100 )= 0.25; The denominator is a multiple of 100 here to make the calculation easier.
Ques: How do you show decimals on a number line? (2 Marks)
Ans: By drawing a dot for each decimal place the decimals on the number line can be shown. For example, to show 0.6 on the number line from 0 to 1, placing 3 dots on the number line: one at 0, one at 0.5, and one at 0.9 is required.
Ques: How to Graph Decimals on a Number Line? (2 Marks)
Ans: By putting the decimal over the unit mark, then moving up or to the right until a number that is greater than or equal to the decimal is reached.
Ques: Can a number line have decimals? (2 Marks)
Ans: A number line can have decimals. By representing real numbers on a line it can be written down, including integers and fractions. They have decimal points in them—for example, 4.3 or -3.5.
Ques: What is the place value of the underlined digit in 45.82? (2 Marks)
Ans: The underlined digit, 8, is in the tenths place. Hence, its place value is 0.8.
Ques: In which place does the underlined digit lie in 56.782? (2 Marks)
Ans: The highlighted digit comes third after the decimal point. The first position following the decimal point is termed tenths, the second hundredths, and the third thousandths. As a result, the digit in question is in the thousandths position.
Ques: Give an example of like decimals. (2 Marks)
Ans: If two decimal numbers have the same number of digits after the decimal point, they are said to be similar decimals. 9.59 and 6.35 are two examples.
Ques: What are some applications of decimals in daily life? (2 Marks)
Ans: Decimal numbers are employed when greater accuracy is required than whole numbers can offer. For example, when we weigh ourselves on the scale, we do not always discover that the weight is equal to a whole number, it can be a fraction. So, in similar cases decimals are very useful.
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