# Java program to display prime numbers from 1 to 100 and 1 to n

The number which is only divisible by itself and 1 is known as prime number. For example 2, 3, 5, 7…are prime numbers. Here we will see two programs: 1) First program will print the prime numbers between 1 and 100 2) Second program takes the value of n (entered by user) and prints the prime numbers between 1 and n. If you are looking for a program that checks whether the entered number is prime or not then see: Java Program to check prime number.

## Program to display the prime numbers from 1 to 100

It will display the prime numbers between 1 and 100.

class PrimeNumbers { public static void main (String[] args) { int i =0; int num =0; //Empty String String primeNumbers = ""; for (i = 1; i <= 100; i++) { int counter=0; for(num =i; num>=1; num--) { if(i%num==0) { counter = counter + 1; } } if (counter ==2) { //Appended the Prime number to the String primeNumbers = primeNumbers + i + " "; } } System.out.println("Prime numbers from 1 to 100 are :"); System.out.println(primeNumbers); } }

Output:

Prime numbers from 1 to 100 are : 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

## Program to display prime numbers from 1 to n

It will display all the prime numbers between 1 and n (n is the number, entered by user).

import java.util.Scanner; class PrimeNumbers2 { public static void main (String[] args) { Scanner scanner = new Scanner(System.in); int i =0; int num =0; //Empty String String primeNumbers = ""; System.out.println("Enter the value of n:"); int n = scanner.nextInt(); scanner.close(); for (i = 1; i <= n; i++) { int counter=0; for(num =i; num>=1; num--) { if(i%num==0) { counter = counter + 1; } } if (counter ==2) { //Appended the Prime number to the String primeNumbers = primeNumbers + i + " "; } } System.out.println("Prime numbers from 1 to n are :"); System.out.println(primeNumbers); } }

Output:

Enter the value of n: 150 Prime numbers from 1 to n are : 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149