Question

If 40% of a number is 800 then find the number?

Answer 1

Hint: To find 40% of a number, we consider the number to be a variable x and then we find 40% of x and equate it to 800 as per given, we solve it for the value of x.

Complete step-by-step answer:

Let the number be x.

Given: 40% of a number is 800

$
   \Rightarrow \dfrac{{40}}{{100}}{\text{ }} \times {\text{ x = 800}} \\
   \Rightarrow \dfrac{2}{5}{\text{ }} \times {\text{ x = 800}} \\
   \Rightarrow 2{\text{ }} \times {\text{ x = 5}} \times {\text{800}} \\
   \Rightarrow {\text{2x = 4000}} \\
   \Rightarrow {\text{x = }}\dfrac{{4000}}{2} \\
   \Rightarrow {\text{x = 2000}}{\text{.}} \\
$

Hence, the number is 2000.

Note: In order to solve such types of questions the key is to use the percentage formula on an unknown and equating it to the given number. Percentage formula states that, if you have to turn a percentage into a decimal, just divide by 100. For example, 25% = 25/100 = 0.25. To change a decimal into a percentage, multiply by 100. So 0.3 = 0.3 × 100 =30%.