1) Use a for loop to print the 5 times table up to 12 x 5
for(int i = 1; i<13; i++) { System.out.println(i*5); }
2) Use a for loop to print the 7 times table up to 12 x 7 in the form “3 x 7 = 21”
for(int i = 1; i<13; i++) { System.out.format("%d x 7 = %d %n",i,i*5); }
3) Use a for loop to print the following sequence: 0.5, 0.4, 0.3, 0.2, 0.1, 0
for(int i = 5; i>=0; i--) { System.out.println((double)i/10); }
4) Use a for loop to print the following sequence: 0.03, 0.02, 0.01, 0, -0.01, -0.02, -0.03
for(int i = 3; i>=-3; i--) { System.out.println((double)i/100); }
5) Use a for loop to print five random numbers between 1 and 10
for(int i = 1; i<11; i++) { System.out.println((int)(Math.random()*5+1)); }
6) Use a for loop to print the first ten square numbers: 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
for(int i = 1; i<11; i++) { System.out.println(i*i); }
7) Use a for loop to print the first ten triangle numbers: 1, 3, 6, 10, 15, 21, 28, 36,45, 55
int triangle = 0; for(int i = 1; i<11; i++) { triangle += i; System.out.println(triangle); }
8) Use a while loop to print the numbers from 1 to 10 inclusive
int count = 1; while (count < 11) { System.out.println(count); count++; }
9) Use a while loop to print the sequence 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1
double number = 9; while (number > 0) { System.out.println(number/10); number--; } }
10) Use a while loop to print the 4 times table up to 12 x 4.
int count = 1; while (count < 13) { System.out.println(count*4); count++; }
11) Use a while loop to print the 9 times table up to 12 x 9 in the form “1 x 9 = 9, 2 x 9=18… ”
int count = 1; while (count < 13) { System.out.format("%d x 9 = %d%n",count,count*9); count++; }
12) Prompt the user to enter a number. Keep a running total of the numbers entered. Loop until the user enters -1, exit the loop and print the total
(Compare this with the answer to 13)
Scanner scan = new Scanner(System.in); int total = 0; int number; do { System.out.println("Enter a number. -1 to exit."); number = scan.nextInt(); total+=number; } while (number != -1); System.out.println("Total is " + (total+1));
13) Prompt the user to enter a number. Keep a running total of the numbers entered. Loop until the user enters -1, exit the loop and print the average
(Compare this with the answer to 12)
Scanner scan = new Scanner(System.in); int total = 0; int number = 0; int count = -1; while(number != -1) { total+=number; count++; System.out.println("Enter a number, -1 to quit"); number = scan.nextInt(); } System.out.println(total + " " + number + " " + count); double average = (double)total/(double)count; System.out.println("Average is " + average);
14) Write a program to test if 91 is prime. Use a while loop to divide 91 by the numbers from 2 to 10. Output True if none of the numbers 91%(number) = 0 for any of the numbers, output False otherwise.
int primep = 13; int count = 2; boolean flag = true; while (count <11) { if(primep % count == 0) flag = false; count++; } System.out.println(flag);
15) Write a program to test if any number is prime. Use a while loop to divide the input by the numbers from 2 to sqrt(input). Output “Prime” if the number is prime, “Not Prime” otherwise.
Scanner scan = new Scanner(System.in); System.out.println("Enter number to be tested"); int primep = scan.nextInt(); int count = 2; boolean flag = true; while (count < Math.sqrt(primep)) { if(primep % count == 0) flag = false; count++; } if(flag) { System.out.println("Prime"); } else { System.out.println("Not Prime"); }
16) Use a while loop to print the sequence 1, -2, 3, -4, 5, -6, 7, -8
int count = 1; while(count < 9) { System.out.println(-(Math.pow(-1,count)*count)); count++; }
17) Use a while loop to calculate pi using the Liebniz formula pi/4 = 1 – 1/3 + 1/5 – 1/7 + 1/9 – … How many iterations do you need to get 3.141?
int count = 1; double total = 1; while(count < 10000) { total = total + ((Math.pow(-1,count)/(2*count + 1))); System.out.println(4*total); count++; }