C++ 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 25% represents (25 / 100) or 0.25. So, 25% of a number b will be calculated as b * (25 / 100) or b * 0.25.
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, C++ programs to solve the above problems are given along with the algorithm, pseudocode and time-complexity of the programs.
Page content(s):
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.
4. End Procedure
3. Time complexity to calculate percentage of a number
Time Complexity: O(1)
4. Programs to calculate percentage
4.1. C++ Program to calculate "What is a% of b?"
/**************************************** alphabetacoder.com C++ program to calculate what is a% of b? *****************************************/ #include <iostream> #include <iomanip> using namespace std; int main() { // declare variables float a, b, x; // take input cout << "Enter values to calculate a% of b" << endl; cout << "Enter a = "; cin >> a; cout << "Enter b = "; cin >> b; // calculate value x = b * (a / 100); // display result upto 3 decimal places cout << fixed << setprecision(3) << x << " is " << a << "% of " << b << endl; return 0; }
Output
Case 1:
Enter values to calculate a% of b
Enter a = 65
Enter b = 150
97.500 is 65.000% of 150.000
Case 2:
Enter values to calculate a% of b
Enter a = 200
Enter b = 20
40.000 is 200.000% of 20.000
4.2. C++ Program to calculate "a is what % of b?"
/***************************************** alphabetacoder.com C++ program to calculate a is what % of b? ******************************************/ #include <iostream> #include <iomanip> using namespace std; int main() { // declare variables float a, b, x; // take input cout << "Enter values to calculate a is what % of b?" << endl; cout << "Enter a = "; cin >> a; cout << "Enter b = "; cin >> b; // calculate value x = (a / b) * 100; // display result upto 3 decimal places cout << fixed << setprecision(3) << a << " is " << x << "% of " << b << endl; return 0; }
Output
Case 1:
Enter values to calculate a is what % of b?
Enter a = 10
Enter b = 30
10.000000 is 33.333% of 30.000000
Case 2:
Enter values to calculate a is what % of b?
Enter a = 30
Enter b = 45
30.000000 is 66.667% of 45.000000
4.3. C++ Program to calculate "a is b% of what?"
/***************************************** alphabetacoder.com C++ program to calculate a is b% of what? ******************************************/ #include <iostream> #include <iomanip> using namespace std; int main() { // declare variables float a, b, x; // take input cout << "Enter values to calculate a is b % of what?" << endl; cout << "Enter a = "; cin >> a; cout << "Enter b = "; cin >> b; // calculate value x = (a / b) * 100; // display result upto 3 decimal places cout << fixed << setprecision(3) << a << " is " << b << "% of " << x << endl; return 0; }
Output
Case 1:
Enter values to calculate a is b % of what?
Enter a = 13
Enter b = 35
13.000 is 35.000% of 37.143
Case 2:
Enter values to calculate a is b % of what?
Enter a = 16.66
Enter b = 75
16.660 is 75.000% of 22.213