Question

A decimal number is multiplied by itself. If the product is 51.84, then the number is ___. (Give answer till one decimal place)

Answer 1

Let the number be x.
Then, product $=x\times x=x^2$
But product = 51.84 [given]
$\therefore x^2=51.84$
$\Rightarrow x=\sqrt{51.84}$
We use long division method to find the square root of 51.84. For that, we will group 2 numbers from right to left and then proceed with the division.

$\begin{array}{cc}& 7.2\\ 7& \overline{51}.\overline{84}\\ & -49\\ 142& 284\\ & -284\\ & 0\end{array}$
$\therefore$ $x=\sqrt{51.84}=7.2$
Hence, the required number is 7.2