# Java : How to generate a random number between two given numbers

## How to find a Random Number Between two given Numbers

Suppose we want to generate a number between two given numbers X and Y then we can use the following two approaches.## Approach 1

- Generate a random number between 0 to (Y - X ) just add this to X. i.e
**X+N**

For, example if we have to calculate a random number between 100 and 150,

then in that case X = 100 , Y = 150,

Then we calculate a number between 0 to (150-100) i.e 0 to 50. Thus, we just need to add this to 100 to get a number in range of 100 to 150.

Then we calculate a number between 0 to (150-100) i.e 0 to 50. Thus, we just need to add this to 100 to get a number in range of 100 to 150.

## Approach 2

- Generate a number N using the
**Math.random()**method such that**( N < X< Y )** - If
**N <= Y - X**then result is**X+N** - else, we add the difference of N from the difference of X and Y i.e
**X + ( N - ( Y - X ))**

For, example if we have to calculate a random number between 100 and 150,

then in that case X = 100 , Y = 150,

- Case 1 : N = 24 ( less than Y- X)

In this case result will be X + N that is 24 + 100 = 124 - Case 2 : N = 88 ( greater than Y-X )

In this case result will be X + ( N - (Y - X)) that is 100 + (88 - (100 - 50)) = 138

package com.ekiras.demo;

public class Rand {

public static void main(String args[]){

System.out.println(sol1(100,150));

System.out.println(sol2(100,150));

}

public static int sol1(int start, int end){

int num = rand(end-start);

return num+start;

}

public static int sol2(int start,int end){

int num = rand(start);

if(num<=end-start)

return num+start;

else{

return start+num-(end-start);

}

}

public static int rand(int n){

return ((int)(Math.random()*n));

}

}

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