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Thread: Write a Java program that accepts an integer (n) and computes the value of n+nn+nnn.

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    Default Write a Java program that accepts an integer (n) and computes the value of n+nn+nnn.

    import java.util.Scanner;
     
    class RicMain 
    {    
    	public static void main(String[] args) 
    	{
    		Scanner ip = new Scanner(System.in);
    		int n, m;
     
    		System.out.print("Input number: ");
    		n = ip.nextInt();
     
    		System.out.printf("%d + %d%d + %d%d%d", n, n, n, n, n, n);
     
    		m = n + 11*n + 111*n;
    		System.out.println(" = " + m);
    	}
    }

    My problem is, for m = n + 11*n + 111*n, it works for numbers 1 - 9, but for 10 and above, it wont work because for example
    if I input 10, it would output: 10 + 1010 + 101010, but for m, it is wrong because 11 * 10 != 1010. So how do I fix this?

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    Super Moderator Norm's Avatar
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    Default Re: Write a Java program that accepts an integer (n) and computes the value of n+nn+nnn.

    m = n + 11*n + 111*n, it works for numbers 1 - 9, but for 10 and above, it wont work
    Please explain why that is supposed to work.
    Where do the values 11 and 111 come from?

    What does that have to do with the post's title: computes the value of n+nn+nnn?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Write a Java program that accepts an integer (n) and computes the value of n+nn+nnn.

    It prints "1010" because you're just concatenating the String "10" twice with System.out.printf("%d + %d%d + %d%d%d", n, n, n, n, n, n). If you want it to print the individual values of 10*1, 10*11, and 10*111, you could store each answer in a separate int and print those ints. Something like this:
    int n1 = n * 1;
    int n2 = n * 11;
    int n3 = n * 111;
     
    System.out.printf("%d + %d + %d", n1, n2, n3); // Prints 10 + 110 + 1110 = 1230
     
    m = n1 + n2 + n3;
    (etc)
    Hope that helps!

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    Default Re: Write a Java program that accepts an integer (n) and computes the value of n+nn+nnn.

    The OP doesn't understand where the values 11 and 111 come from and why they only work with single digit values.
    Those multipliers need to be computed for values with more digits. For example given a value of 123 and a desired value of 123123 the multiplier would be 1001.
    The leading 1 * 10^3 (^3 because of 3 digits) + 1
    If you don't understand my answer, don't ignore it, ask a question.

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