# 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 %

**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 <bits/stdc++.h> ` `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; ` `} ` |

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## 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 ` |

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## 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 ` |

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## 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. ` |

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## PHP

`<?php ` `// PHP implementation of the approach ` ` ` `// Function to return the ` `// required rate percentage ` `function` `Rate(` `$N1` `, ` `$N2` `) ` `{ ` ` ` `$rate` `= (` `$N2` `- ` `$N1` `) * 100 / ` `$N1` `; ` ` ` ` ` `return` `$rate` `; ` `} ` ` ` `// Driver code ` `$N1` `= 100; ` `$N2` `= 120; ` ` ` `echo` `Rate(` `$N1` `, ` `$N2` `), ` `"%"` `; ` ` ` `// This code is contributed by AnkitRai01 ` `?> ` |

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**Output:**

20 %

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