Program to display first n prime numbers
import java.util.Scanner; class PrimeNumberDemo { public static void main(String args[]) { int n; int status = 1; int num = 3; //For capturing the value of n Scanner scanner = new Scanner(System.in); System.out.println("Enter the value of n:"); //The entered value is stored in the var n n = scanner.nextInt(); if (n >= 1) { System.out.println("First "+n+" prime numbers are:"); //2 is a known prime number System.out.println(2); } for ( int i = 2 ; i <=n ; ) { for ( int j = 2 ; j <= Math.sqrt(num) ; j++ ) { if ( num%j == 0 ) { status = 0; break; } } if ( status != 0 ) { System.out.println(num); i++; } status = 1; num++; } } }
Output:
Enter the value of n: 15 First 15 prime numbers are: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47
Program to display first 100 prime numbers
To display the first 100 prime numbers, you can either enter n value as 100 in the above program OR write a program like this:
class PrimeNumberDemo { public static void main(String args[]) { int n; int status = 1; int num = 3; System.out.println("First 100 prime numbers are:"); System.out.println(2); for ( int i = 2 ; i <=100 ; ) { for ( int j = 2 ; j <= Math.sqrt(num) ; j++ ) { if ( num%j == 0 ) { status = 0; break; } } if ( status != 0 ) { System.out.println(num); i++; } status = 1; num++; } } }
Output:
First 100 prime numbers 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 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397 401 409 419 421 431 433 439 443 449 457 461 463 467 479 487 491 499 503 509 521 523 541
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