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Thread: Removing digits
 03262011, 04:01 AM #1Member
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Removing digits
I am trying to write a program that randomly generates a number up to five digits and then prints the sum of the digits. I know how to generate the number and I think I am removing the first number correctly, but I get lost after that. Here's what I have tried. I know that my output isn't correct but I have it set up like this so that I can see if I am pulling the numbers out correctly. Once I have that figured out I'll change the output to sum the individual digits.
Java Code:public class ProgrammingProblemOne { public static void main(String[] args) { //generate random number int n = (int)Math.floor(Math.random()*100000+1); //pull out first digit int tenThousands = n / 10000; //pull out second digit int thousands = n / 1000; /pull out third digit int hundreds = n / 100; //pull out fourth digit int tens = n / 10; //pull out fifth digit int ones = tens / 1; System.out.println("Generated number: " + n); System.out.println("First digit: " + tenThousands); System.out.println("Second digit: " + thousands); System.out.println("Third digit : " + hundreds); System.out.println("Fouth digit: " + tens); System.out.println("Fifth digit: " + ones); } }
 03262011, 04:37 AM #2Moderator
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I know that my output isn't correct
Could you describe what the output is?
 03262011, 04:37 AM #3Senior Member
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If you have a 3 digit number like "321", then you know you have 3 hundreds.
To find out how many tens you have, you need to subtract 300 from 321 and you have 21 left. Now you can find out how many tens you have.
 03262011, 04:55 AM #4Member
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The output is eventually going to be the sum of the individual digits within the randomly generated number. For instance if the number is 97634, then I need to add 9 + 7 + 6 + 3 + 4.
I know how to do that part. It's breaking the numbers down into their single digits that I'm having problems with. So to help with that, I have made the output to see whether I am successfully pulling out the single digits.
 03262011, 04:56 AM #5Member
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 03262011, 05:00 AM #6Moderator
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I understand what you want the output to be eventually. I was wondering if you could describe what the output is. You said the output is not correct, but what is incorrect about it?
 03262011, 05:35 AM #7Member
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 03262011, 05:53 AM #8Senior Member
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That works if you know the number but I don't know how I would do that with a randomly generated number.
In my example you start by dividing the random number by 100 to get the first digit. Then you multiply that digit by 100 to get the amount to subtract from the random number. You repeat for the 10's until all you are left with is a single digit.
 03262011, 09:42 AM #9Senior Member
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Java Code:int ones = tens / 1;
Instead, use the modulus operator. To isolate the last digit, use:
Java Code:int ones = n % 10;
Rather than having five separate variables for the digits, I'd recommend using an array. That way, you can loop over it, and if you write your code properly it can adapt to numbers of any length instead of being fixed at 5 digits.
 03262011, 09:57 AM #10
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As iron lion stated, can easily be done with a loop, a 5 item array and %(modulus) and /(division). That being said, give it a shot, start by a number like 321 and try and isolate the 1, then change the number to 32. Do this with %, / and you are mostly done.
 03262011, 05:29 PM #11Member
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 03262011, 05:32 PM #12Member
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LOL! I guess that was pretty stupid wasn't it. I'm not sure what I was thinking when I did that.
Instead, use the modulus operator. To isolate the last digit, use:
Java Code:int ones = n % 10;
Rather than having five separate variables for the digits, I'd recommend using an array. That way, you can loop over it, and if you write your code properly it can adapt to numbers of any length instead of being fixed at 5 digits.
 03262011, 05:35 PM #13Member
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 03262011, 10:12 PM #14Member
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Got it!!! It took forever to figure it out but I finally got it. Thank you all for your help! Here's the code:
Java Code:public class ProgrammingProblemOne { public static void main(String[] args) { //generate random number int n = (int)Math.floor(Math.random()*100000+1); //isolate first digit int tenThousands = n / 10000; //isolate second digit int a = n / 1000; int thousands = a % 10; //isolate third data int b = n /100; int hundreds = b % 10; //isolate fourth digit int c = n / 10; int tens = c % 10; //fifth digit int d = tens % 10; int ones = n % 10; //output System.out.println("Generated number: " + n); System.out.println("First digit: " + tenThousands); System.out.println("Second digit: " + thousands); System.out.println("Third digit : " + hundreds); System.out.println("Fourth digit: " + tens); System.out.println("Fifth digit: " + ones); System.out.println("The sum of all digits is " + (tenThousands + thousands + hundreds + tens + ones)); } }
 03262011, 10:18 PM #15Member
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