Decimals

Introduction: What are Decimals in Maths?

A decimal is defined as a number expressed in decimal notation and generally applied to values that have a fractional part and separated from the integer side by a decimal separator.

Now let’s see an example

Here is the number “thirty-four and seven-tenths” written as a decimal number:

Decimal Place Value
The decimal point goes between Ones and Tenths

34.7 has 3 Tens, 4 Ones and 7 Tenths
Decimal in Maths

Place Value in decimals

The place value system is used to define the position of a digit in a number which helps to determines its value. When we write specific numbers, the position of each digit is important.

Example:

For instance, let’s consider the number 456.

  • The position of “6” is in One’s place, which means 6 ones (i.e. 6).
  • The position of “5” is in the Ten’s place, which means 5 tens(i.e. fifty).
  • The position of “4” is in the Hundred’s place, which means 4 hundred.
  • As we go left, each position becomes ten times greater.

Hence, we read it as “Four hundred fifty-six”.

Decimal Number
As we move left, each position is 10 times bigger!

Tens are 10 times bigger than Ones.

Hundreds are 10 times bigger than Tens.

And

Each time we move right every position becomes 10 times smaller

From Hundred’s to Ten’s, to Ones

But if we continue past Ones?
Decimal Place Value

What is 10 times smaller than Ones?

\(\frac{1}{10}ths\) (Tenths) are!

Before that, we should first put a decimal point,

So we already know that where we put that decimal point.

How to Write Decimal
We say the above example as four hundred and fifty-six and eight-tenths but

We usually just say four hundred and fifty-six point eight.

Types of Decimal Numbers

Decimal Numbers may be of different kinds, namely

Recurring Decimal Numbers (Repeating or Non-Terminating Decimals)

Example-

3.125125 (Finite)

3.121212121212….. (Infinite)

Non-Recurring Decimal Numbers (Non Repeating or Terminating Decimals):

Example:

3.2376 (Finite)

3.137654….(Infinite)

Decimal Fraction- It represents the fraction whose denominator in powers of ten.

Example:

81.75 = 8175/100

32.425 = 32425/1000

Converting the Decimal Number into Decimal Fraction:

For the decimal point place a “1” in the denominator and remove the decimal point.

“1” is followed by a number of zeros equal to the number of digits following the decimal point.

For Example:

8  1 . 7  5

↓ ↓ ↓

1 0 0

81.75 = 8175/100

8 represents the power of 101 that is the tenths position.

1 represents the power of 10that is the units position.

7 represents the power of 10-1 that is the one-tenths position.

5 represents the power of 10-2 that is the one-hundredths position.

So that is how each digit is represented by a particular power of ten in the decimal number.

Place Value of Decimal Numbers

The place value is obtained by multiplication of the digit in the decimal number with its power of ten that the digit holds at its position.

Place Value Chart

The power of ten can be found using the following Place Value Chart:

Place Value Chart

The digits to the left of the decimal point are multiplied with the positive powers of ten in increasing order from right to left.

The digits to the right of the decimal point are multiplied with the negative powers of 10 in increasing order from left to right.

Following the same example 81.75

The decimal expansion of this is :

{(8*10)+(1*1)} + {(7*0.1)+(5*0.01)}

Where each number is multiplied by its associated power of ten.

To learn more on decimals, division of decimals and operations of converting fractions to decimals, Register with BYJU’S and strengthen your skills.

2 Comments

  1. I want Maths question paper of decimal

    1. Here you could find the Decimal question paper for Class 6 and 7 – https://byjus.com/maths/decimal-worksheets/

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