Question

What is $80\%$ of 45?

Answer 1

Hint: To find the value $80\%$ of 45 we will remove the percentage sign and divide 80 by 100. Then we will simplify it by dividing the numerator by the same number till we get a pair of co-prime numbers. Then multiply the result by 45 and simplify it to get the desired answer.

Complete step by step solution:
To obtain $80\%$ of 45 we will convert it in fraction by dividing it by 100 and removing the percent sign as follows:
$80\%=\dfrac{80}{100}$
Now, we will simplify the above value by dividing the numerator and denominator by 10 as,
$\begin{align}
  & \Rightarrow \dfrac{\dfrac{80}{10}}{\dfrac{100}{10}} \\
 & \Rightarrow \dfrac{8}{10} \\
\end{align}$
We will simplify it further by dividing numerator and denominator by 2 and get,
$\begin{align}
  & \Rightarrow \dfrac{\dfrac{8}{2}}{\dfrac{10}{2}} \\
 & \Rightarrow \dfrac{4}{5} \\
\end{align}$
So we can write
$80\%=\dfrac{4}{5}$
Next, we will multiply 45 by the above value as,
$\begin{align}
  & \Rightarrow \dfrac{4}{5}\times 45 \\
 & \Rightarrow 4\times 9 \\
 & \Rightarrow 36 \\
\end{align}$
Hence, $80\%$ of 45 is 36.

Note: The percentage term used is a number or we can say ratio which is expressed as a fraction of 100. It is denoted by percent sign $\%$. It doesn’t have any unit of measurement. Percentage means a part per hundred. It can be represented in decimal form; the most common use of percentage is in exams where the percent of the total marks in all subjects is calculated for every student. We can also use a direct method to find the solution. The formula is:
$P\%$ of Number $=X$
Where $X$ is the answer
So we can write:
$80\%$ of $45=X$
On Removing percentage sign and divide 80 by 100 we get,
$\begin{align}
  & \Rightarrow \dfrac{80}{100}\times 45=X \\
 & \Rightarrow \dfrac{8}{10}\times 45=X \\
 & \therefore 36=X \\
\end{align}$
So we get $X=36$ which is the desired answer.