## >_ Problem

Joe’s Pizza Palace needs a program to calculate the number of slices a pizza of any size can be divided into. The program should perform the following steps:

A) Ask the user for the diameter of the pizza in inches.

B) Calculate the number of slices that may be taken from a pizza of that size.

C) Display a message telling the number of slices.

To calculate the number of slices that may be taken from the pizza, you must know the following facts:

- Each slice should have an area of 14.125 inches.
- To calculate the number of slices, simply divide the area of the pizza by 14.125.
- The area of the pizza is calculated with this formula:

Area = πr^2

*NOTE: π is the Greek letter pi. 3.14159 can be used as its value. The variable r is the radius of the pizza. Divide the diameter by 2 to get the radius.*

Make sure the output of the program displays the number of slices in fixed point notation, rounded to one decimal place of precision. Use a named constant for pi.

## >_ Solution

```
#include <iostream>
#include <cmath> // pow()
#include <iomanip>
using namespace std;
int main()
{
// Constants
const float SLICE_AREA_SIZE = 14.125,
PI = 3.14159;
const int TWO = 2;
// Variables
float d, // Diameter
r, // Radius
Area,
num_of_slices;
// Ask the user for the diameter of the pizza in inches.
cout << endl;
cout << "What is the diameter of the pizza in inches? ";
cin >> d;
// Calculate the # of slices that may be taken from a pizza
// of that size
r = d / TWO; // Radius
Area = PI * pow(r, TWO);
num_of_slices = Area / SLICE_AREA_SIZE;
// Display a message telling the number of slices.
cout << setprecision(1) << fixed;
cout << "Number of slices = ";
cout << num_of_slices << endl;
cout << endl;
// Terminate Program
return 0;
}
```

## >_Get The Book!

## >_ Video Walk Through

This video includes a step by step process of how I solve programming challenge #20.

## >_That’s it!

Thank you for taking interest in what I do! I hope it was helpful for you as much as it helped me along my journey in learning to code!

## >_ Also Check Out:

Category: Starting Out With C++ | Chapter 3 | Programming Challenge Solutions