Flexi Says:
Apercent is a ratio that describes a quantity out of 100. A percent is also a part of a whole. Finding the percent of a number is the part of a number that is equivalent to the percent.
Steps to find the percentage of a number - Method 1
Let's, find 40% of 40 using proportion.
First, write the percent as a fraction. 40% is also 40 out of 100.
@$$\begin{align*}40\%=\frac{40}{100}\end{align*}@$$
Next, write a proportion to find the equivalent fraction of 40% of 40. The second fraction is the unknown quantity, represented by@$\begin{align*}x\end{align*}@$, over the whole, 40.
@$$\begin{align*}\frac{40}{100}=\frac{x}{40}\end{align*}@$$
Now, cross-multiply to find the cross-product. To cross-multiply, multiply thenumerator of one fraction with the denominator of the other fraction. The products should be equal.
@$$\begin{align*}40(40)=100x\end{align*}@$$
Finally, simplify the equation to solve for @$\begin{align*}x\end{align*}@$. Multiply 40 by 40 and divide both sides by 100.
@$$\begin{align*}40(40)&=100x\\[6pt]\frac{1600}{100}&=\frac{100x}{100}\\[6pt]16&=x\end{align*}@$$
Hence, 40% of 40 is 16.
Steps to find the percentage of a number - Method 2
Another method is to use keywords and multiplication. Let's look again at the problem.
What is 40% of 40?
First, look for keywords that suggest an operation. The word "of" tells you to multiply 40 by 40%.
Next, convert 40% to a decimal.
@$$\begin{align*}40\%=0.4\end{align*}@$$
Then, write an equation to find the unknown number, @$\begin{align*}x\end{align*}@$.
@$$\begin{align*}x=40\times 0.4\end{align*}@$$
Finally, solve for @$\begin{align*}x\end{align*}@$ by multiplying 40 by 0.4.
@$$\begin{align*}x=40\times 0.4=16\end{align*}@$$ The answer is the same. 40% of 40 is 16.
Steps to find the percentage of a number - Method 3
The relationship@$\begin{align*}\text{percent} = \frac{\text{part}}{\text{whole}}\end{align*}@$ can be used to solve for a percent using the part and the whole. By multiplying the whole by the other side you get the following equation:@$$\begin{align*}\text{percent} \cdot \text{whole}= \text{part}\end{align*}@$$
Step 1: Divide the percentage by 100.
Step 2: Multiply the result by the number you want to find the percentage of.
For example, find 40% of 40.
Part = ?
Whole = 40.
Percent = @$\begin{align*}40\% \rightarrow \frac{40}{100}.\end{align*}@$
@$$\begin{align*}\text{Percent} \cdot \text{Whole}& = \text{Part} \\\frac{40}{100} \cdot 40 & = \text{Part} \\16 & = \text{Part}\end{align*}@$$
∴ 40% of 40 is 16.
To learn more about percentages, click here!