### Theory:

We can follow the below steps to find the square of the decimal numbers.
Step 1: Calculate the square of the given decimal number without the decimal.

Step 2: Put the decimal point in the obtained number such that it is twice that of the original number.

Note:

(i) If the original number contains single decimal, then the square of that number will have double decimal.

Number of decimals in the given number $$\times 2 = 1 \times 2 = 2$$

(ii) If the original number contains double decimal, then the square of that number will have four decimal.

Number of decimals in the given number $$\times 2 = 2 \times 2 = 4$$
Example:
Find the square of $2.4$.

Step 1: Calculate the square of the given number without decimal.

${\left(24}^{2}\right)=24×24=576$.

Step 2: Now, put the decimal point in the obtained number such that it is twice that of the original number.

That is, the given number has a single decimal, and the answer would be the double decimal.

${2.4}^{2}=5.76$

Therefore the square of a given decimal number is $2.4$ $$=$$ $5.76$.