# using formula in C++

##### EXERCISE

- Programming in C++
- store a full length of name in C++
- find out in given number, even or odd in C++
- using formula in C++
- arithmetical progression using C++
- found a given number is positive or negative in C++
- find a largest number in any three given number
- for-loop
- while-loop
- do-while loop
- add array elements total in C++
- Add different array element with each other
- structure programs in C++
- function exercise
- file handling programs in C++

In this page, two programs are given. In which real world formulas have been used,

## a simple demonstration to find out simple interest

In this program, we will find simple interest

As we know that we use its formula to find out the simple interest. like

`si = (principle*rate*time/100);`

In this formula, we have input period, rate and time from the user.

Here is the program,

```
#include<iostream.h>
#include<conio.h>
void main()
{
clrscr();
int si,principal,rate,time;
cout<<"Enter Principal, rate, time: ";
cout<<"\nPrincipal: "; cin>>principal;
cout<<"Rate(in %) : "; cin>>rate;
cout<<"Time(days) : "; cin>>time;
si = (principal*rate*time/100);
cout<<"Simple interest: "<<si;
getch();
}
```

**OUTPUT:- **
Enter Principal, rate, time:
Principal : 100
Rate(in %) : 5
Time(days) : 2
Simple interest: 10

In the program, we have declared three variables. such as,

`int principal, rate, time, si`

Where, the user has been asked for input for variables period, rate and time. suppose these input are

principal = 100 rate = 5 time = 2

and variable si store these variable’s result,

`si = (principal*rate*time)/100`

means,

`si = (100*5*2)/100`

And in the last statement, the value of variable si is printed which is 10.

Thus program is executed successfully

Here is another one program,

## Convert Fahrenheit degree to Celsius

in this program we convert fahrenheit degree to celsius

Like the program above, we will use the formula here

`celsius = (farhenheit-32)*5/9;`

Here is the program,

#include<iostream.h> #include<conio.h> void main() { clrscr(); int farhenheit,celsius; cout<<"Enter Fahrenheit Degree: "; cin>>farhenheit; celsius = (farhenheit-32)*5/9; // using formula cout<<"\nIn Celsius: "<<celsius; getch(); }

OUTPUT:-Enter Fahrenheit degree: 23 In Celsius: -5

**Explanation:**

In the program, we have asked the user to enter the degree farhenheit. Which will be stored in the variable farhenheit, such as,

`farhenheit = 23`

After this we have used the formula to get celsius degree, so

`celsius = (23-32)*5/9`

And in the last statement, the value of the variable calsius is printed.

Similarly in C++, we can also create many more programs where we can use the formulas.