Question

How do you write $4.2$ as a percent?

Answer 1

Hint: We know that one percent is the value one hundredth. From this, we learn that one percent of a number is equal to one hundredth of that number. Therefore, a number can be written as a percent by multiplying it with $\dfrac{1}{100}.$

Complete step by step answer:
We know that the terminology percent means that we consider the total amount of a whole of a quantity as a hundred. So, we calculate the amount of a part of this quantity on the basis of a hundred. This value will be said in terms of a hundred.
Suppose that we have $x$ amount of quantity considered to be a total of a hundred. In this situation, we will say that the amount of the quantity we have is $x$ out of hundred. That is, $\dfrac{1}{100}$ of $x.$
If we say that $x$ percent of something, then we mean $\dfrac{x}{100}$ of it.
Here, we want to write the given number as a percent.
Let us multiply and divide the given number $4.2$ with $100.$
As a result of the multiplication and division of the same number which will not make any change to the given number, we will get $4.2\times \dfrac{100}{100}.$
When we multiply $4.2$ with $100,$ we will get $4.2\times 100=42\times 10=420.$ First, by using $10$ in hundred, we removed the decimal point and then we multiplied the obtained value with the remaining $10$ to get $420.$
So, we will get $4.2\times \dfrac{100}{100}=\dfrac{420}{100}.$
We have already learnt that one percent of a number is equal to one hundredth of that number.
So, we will get $\dfrac{420}{100}=420\%.$

Hence $4.2$ is $420\%.$

Note: We can directly find the percent notation by multiplying the number with hundred. That is,$4.2\times 100=420\%.$ Remember that when we have a specific value, we call it percent. And when we do not have a specific value, we say percentage.