Sum of Digits of a Number in Java

Steps to Find the Sum of Digits of a Number in Java

Input any integer number (or the number can be taken by own). After that, we will apply the modulus and division operations to determine the sum of the digits of the number. Let's look at the steps.

1. Firstly, we initialize the variable $n$ with the number. We also initialize a variable sumOfDigits as $0$.
2. Next, we will find the remainder using the modulo operator, which will give us the last digit of the number.
3. After that, we will constantly add the obtained digit(remainder) to the sumOfDigits variable.
4. At the same time, we also need to divide the number $n$ by $10$, which removes the last digit of the number.
5. Repeat steps $2$–$4$ until the number $n$ is equal to $0$.

Sum of Digits of a Number in Java

By using for loop The for loop iterates until $n!=0$, then add the remainder of $n/10$ to the sumOfDigits until $n!=0$ is false. If $n=0$, the for loop is interrupted, and the sum is printed.

Output:

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Sum of Digits of a Number in Java By using Function

We can also make our code more modular and organized by putting it inside a function. The function can be called from anywhere, and it will return the sum of digits, and we need not write its implementation again and again.

Output:

Sum of Digits of a Number in Java By using Recursion

Sum of digits of a number can also be calculated with the help of recursion. Here we will use $n == 0$ as the base condition.

The function will keep on calling itself till the base condition is met. Each time the last digit is chopped, the result from the remaining number is used again to calculate the remaining sum recursively.

In the program given below, the above conditions are written with the help of a ternary operator. If the number is not zero, run the code after the colon (:) in the ternary operator; otherwise output 0. The procedure sumOfDigits() is called recursively.

Output:

Sum of Digits of a Number in Java By using Command Line Arguments

Now, to calculate the sum of the digits of a number, we'll use command line arguments. The main method's "String args[]" will receive the command line parameters. We transform the value at index 0 to long using Long.parseLong(arg[0]), where Long is the wrapper class.

Output: