Steps involved in finding a percent of a given number

Step I– Obtain the number, say x.

Step II– Obtain the required percent, say P %.

Step III– Multiply x by P and divide by 100 to obtain the required P % of x
    i.e.,                        P% of x = \(\frac{ P}{ 100}\) * x

Illustrative Examples

Example 1: Find
                    (i)  30% of Rs 180            (ii) 13% of Rs 6500            (iii) 16% of 25 litres
Solution.   We know that P% of x is equal to \(\frac{ P }{ 100}\) * x. So, We have

(i) 30% of Rs 180 = Rs ( \(\frac{ 30 }{ 100}\) x 180) = Rs 54
               

(ii) 13% of Rs 6500 = Rs ( \(\frac{ 13 }{ 100}\) x 6500 ) = Rs 845
               

(iii) 16% of 25 litres = Rs ( \(\frac{ 16 }{ 100}\) x 25) = 4 litres

Example 2: If 23% of a is 46, then find a.

Solution. We have,

23% of a = \(\frac{ 23 }{ 100}\) x a.
           

But, 23% of a is given as 46.
           

Therefore,   \(\frac{ 23 }{ 100}\) x a => a = 46 x \(\frac{ 100 }{ 23 }\)
          

=> a = 200

Example 3: 72% of 25 students are good at Mathematics. How many are not good at it?

Solution. We have,

Number of students who are good at Mathematics
 

= 72% of 25

= \(\frac{ 72 }{ 100}\) x 25 = 18