Dividing Decimals by Whole Numbers and Decimals

Results for Arun’s quarterly tests are out.

His elder brother asked his result, Arun said that he scored , , , out of in four subjects.

His brother asked him to find the average marks of the four subjects.

He also told him how to find average, first add the marks of all the four subjects and divide the sum by .

Arun found the sum of marks, but it was a decimal and he was not sure how to divide a decimal by .

Let’s understand division of a decimal number by a whole number

Here the decimal number is divided by the whole number

The fraction formed can also be written in the division form.

Now the decimal is written as fraction

For division of fractions, is replaced by its reciprocal and multiplication sign replaces the division sign.

Multiplication of two fractions can be seen as multiplication of their numerators and denominators.

This can be simplified by using the commutative law in numerator.

Now, the result is split into two fractions.

And this can be simplified by reducing the second fraction.

So, dividing the decimal when divided by gives .

Let’s understand the division of a decimal number by a decimal number.

Let’s divide the decimal by another decimal .

The fraction can be written in division form also.

Now, simply convert the two decimals into fractions.

Then, we will replace the division symbol with multiplication by simply invert the second fraction.

And this can be simplified further to .

To divide a decimal by a whole number or by a decimal number, first we convert the decimal into fraction.

And then proceed with the division of a fraction by a whole number.

Now for Arun’s problem, the decimal is divided by the whole number .

Revision

To divide a decimal by a whole number or by a decimal number, first we convert the decimal into fraction.

And then proceed with the division of a fraction by a whole number.

The End