Consider the above decimal number which is to be divided by 10.

This division can be written as shown by converting the decimal number into its fraction.

Now, let's divide 315 by 100 using long division.

So when, $315$ is divided by $100$, we got 3.15 as the result.

Let's divide the same decimal number by 100.

Dividing a Decimal Number by 100

Consider the above decimal number which is divided by 100.

This can be written as shown.

Now, let's divide 315 by 1000 using long division.

That is, we saw that in long division, $315$ when divided by divisor $1000$, the answer is 0.315

Similarly, let's divide the same decimal number by 1000.

Dividing a Decimal Number by 1000

Consider the above decimal number which is divided by 1000.

This can be written as shown.

Now, let's divide 315 by 10000 using long division.

That is, we saw that in long division, $315$ when divided by divisor $10000$, the answer is 0.0315.

Here in all the above divisions, We saw that, while dividing a decimal number by 10, 100, or 1000, the digits of the number and the quotient remain same.

But the decimal points in the quotient shift to the left by as many places as there are zeros after 1.

That is, when a 31.5 is divided by 10, decimal points shifts left by 1 place as shown.

Similarly, when a number is divided by 100, decimal points shifts left by 2 places.

Here again, when a decimal number is divided by 1000, decimal points shifts left by 3 places.

Using the above observation, let's divide 2.38 by 10 without doing the actual long division.

Since 10 has 1 zero, $∴$ the decimal point in the quotient will move to left by 1 place.

When 2.38 is divided by 100, the decimal point will move to the left by 2 places.

When 2.38 is divided by 1000, the decimal point will move to the left by 3 places.

Revision

When a decimal number is divided by 10, the decimal will move to the left by 1 place.

When a decimal number is divided by 100, the decimal will move to the left by 2 places.

When a decimal number is divided by 1000, the decimal will move to the left by 3 places.