Question

Find the square of: $ 6.3 $
 $
  A.\,\,39.69 \\
  B.\,\,39.56 \\
  C.\,\,39.60 \\
  D.\,\,39.03 \\
  $

Answer 1

Hint: Calculating the square of a number using normal multiplication method. First, we will change the decimal part of the number to $ 1 $ by $ 10 $ the form. ( $ 63 $ Divided by $ 10 $ ) Then we will multiply the term in fraction form with itself, thus, finding the square.

Complete step-by-step answer:
To find squares of any number there are different ways.
IN this method we write two times a multiplication whose square is required.
Then, converting decimal terms to fraction terms and multiplying numerator with numerator and denominator with denominator.
And then placing a decimal sign in the result obtained after multiplication to get the required square of the given number.
This is done as:
\[
{(6.3)^2} = 6.3 \times 6.3 = \dfrac{{63}}{{10}} \times \dfrac{{63}}{{10}} = \dfrac{{3936}}{{100}} \\
= 39.69 \;
 \]
Also, we can find square of given number by using identity $ {\left( {a + b} \right)^2} = \left( {{a^2}} \right) + {\left( b \right)^2} + 2\left( a \right)\left( b \right) $
For this taking ‘a’ as $ 60\,\,and\,\,b\,\,as\,\,0.3 $
Then we have:
  $
 {(6)^2} + {(0.3)^2} + 2(6)(0.3) \\
 \Rightarrow 36 + 0.09 + 3.6 \\
 = 39.69 \;
  $
On using different methods there are different ways or different steps involved.
But the final answer in each case will be the same.
So, the correct answer is “Option A”.

Note: The square of a number is basically multiplying the number by itself. After multiplying the term by itself we still got the new term in fraction form ( $ 3936 $ divided by $ 100 $ ). Thus, we changed the term to decimal form since the term is divided by $ 100 $ with two zeroes.