**Python programs to calculate the percentage of a number** have been given below. A percentage is represented as a number or a ratio which is a fraction of 100. It is denoted by the symbol '%'. For example 50% represents (50 / 100) or 0.50. So, 50% of a number *b* will be calculated as *b* * (50 / 100) or *b* * 0.50.

Suppose a and b are two numbers. Then, the solution to the percentage problem is obtained by answering any of the following queries.

(i) What is *a*% of *b*?

(ii) *a* is what % of *b*?

(iii) *a* is *b*% of what?

Let's assume *a* = 15 and *b* = 60, then the solutions w.r.t the above queries:

(i) ___ is *a*% of *b* := 15% of 60 := 60 * (15 / 100) := 9

(ii) *a* is ___ % of *b* := (15 / 60) * 100 := 25%

(iii) *a* is *b*% of ___ := (15 / 60) * 100 := 25

In the following section, Python programs to solve the above problems are given along with the algorithm, pseudocode and time-complexity of the programs.

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## 1. Algorithm to calculate percentage of a number

1. Take a number *a* as input.

2. Take another number *b* as input where b% of a is to be calculated.

3. Calculate *a * (b / 100)* and declare it as the output.

## 2. Pseudocode to calculate percentage of a number

**Input** : Two numbers a, b

**Output** : b% of a

1. **Procedure** percentage(a, b):

2.

3. **Return** x

4. **End Procedure**

## 3. Time complexity to calculate percentage of a number

**Time Complexity: O(1)**

## 4. Programs to calculate percentage

## 4.1. Python Program to calculate "What is a% of b?"

# ********************************************* # alphabetacoder.com # Python program to calculate what is a% of b? # ********************************************* # take input print("Enter values to calculate a% of b") a = float(input("Enter a = ")) b = float(input("Enter b = ")) # calculate value x = b * (a / 100) # display result upto 3 decimal places print(round(x, 3), "is", round(a, 3), "% of", round(b, 3))

Output

Enter values to calculate a% of b

Enter a = 30

Enter b = 70

21.0 is 30.0 % of 70.0

## 4.2. Python Program to calculate "a is what % of b?"

# ********************************************* # alphabetacoder.com # Python program to calculate a is what % of b? # ********************************************* # take input print("Enter values to calculate a is what % of b?") a = float(input("Enter a = ")) b = float(input("Enter b = ")) # calculate value x = (a / b) * 100 # display result upto 3 decimal places print(round(a, 3), "is", round(x, 3), "% of", round(b, 3))

Output

Enter values to calculate a is what % of b?

Enter a = 120

Enter b = 240

120.0 is 50.0 % of 240.0

## 4.3. Python Program to calculate "a is b% of what?"

# ********************************************* # alphabetacoder.com # Python program to calculate a is b% of what? # ********************************************* # take input print("Enter values to calculate a is b %% of what?") a = float(input("Enter a = ")) b = float(input("Enter b = ")) # calculate value x = (a / b) * 100 # display result upto 3 decimal places print(round(a, 3), "is", round(b, 3), "% of", round(x, 3))

Output

Enter values to calculate a is b % of what?

Enter a = 27

Enter b = 81

27 is 81% of 33.333