# Program to find the rate percentage from compound interest of consecutive years

Given two integers N1 and N2 which is the Compound Interest of two consecutive years. The task is to calculate the rate percentage.

Examples:

Input: N1 = 660, N2 = 720
Output: 9.09091 %

Input: N1 = 100, N2 = 120
Output: 20 %

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The rate percentage can be calculated with the formula ((N2 – N1) * 100) / N1 where N1 is the compound interest of some year and N2 is the compound interest for the next year.

Let us consider the 1st Example:
The difference between the Compound interest in the two consecutive years is because of the interest received on the previous year interest. Therefore,
–> N2 – N1 = N1 * (Rate / 100)
–> 720 – 660 = 660 * (Rate / 100)
–> (60 / 660) * 100 = Rate
–> Rate = (100 / 11) = 9.09% (Approx)

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to return the ` `// required rate percentage ` `float` `Rate(``int` `N1, ``int` `N2) ` `{ ` `    ``float` `rate = (N2 - N1) * 100 / ``float``(N1); ` ` `  `    ``return` `rate; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `N1 = 100, N2 = 120; ` ` `  `    ``cout << Rate(N1, N2) << ``" %"``; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation of the approach ` ` `  `class` `GFG  ` `{ ` ` `  `    ``// Function to return the ` `    ``// required rate percentage ` `    ``static` `int` `Rate(``int` `N1, ``int` `N2) ` `    ``{ ` `        ``float` `rate = (N2 - N1) * ``100` `/ N1; ` ` `  `        ``return` `(``int``)rate; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args)  ` `    ``{ ` `        ``int` `N1 = ``100``, N2 = ``120``; ` ` `  `        ``System.out.println(Rate(N1, N2) + ``" %"``); ` `    ``} ` `} ` ` `  `// This code has been contributed by 29AjayKumar `

## Python 3

 `# Python 3 implementation of the approach ` ` `  `# Function to return the ` `# required rate percentage ` `def` `Rate( N1, N2): ` `    ``rate ``=` `(N2 ``-` `N1) ``*` `100` `/``/` `(N1); ` ` `  `    ``return` `rate ` ` `  `# Driver code ` `if` `__name__ ``=``=` `"__main__"``: ` `    ``N1 ``=` `100` `    ``N2 ``=` `120` ` `  `    ``print``(Rate(N1, N2) ,``" %"``) ` ` `  `# This code is contributed by ChitraNayal     `

## C#

 `// C# implementation of the approach ` `using` `System; ` ` `  `class` `GFG ` `{ ` `     `  `    ``// Function to return the ` `    ``// required rate percentage ` `    ``static` `int` `Rate(``int` `N1, ``int` `N2) ` `    ``{ ` `        ``float` `rate = (N2 - N1) * 100 / N1; ` ` `  `        ``return` `(``int``)rate; ` `    ``} ` ` `  `    ``// Driver code ` `    ``static` `public` `void` `Main () ` `    ``{ ` `        ``int` `N1 = 100, N2 = 120; ` ` `  `        ``Console.WriteLine(Rate(N1, N2) + ``" %"``); ` `    ``} ` `} ` ` `  `// This code has been contributed by ajit. `

## PHP

 ` `

Output:

```20 %
```

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