In this article, we are going to find first and last digit of a number in Java.

To find first and last digit of any number, we can have several ways like using modulo operator or pow() and `log()`

methods of `Math`

class etc.

Table of Contents

Before moving to example, let’s first create an algorithm to find first and last digit of a number.

## Algorithm

`Step 1:`

Take a number from the user.`Step 2:`

Create two variables `firstDigit`

and `lastDigit`

and initialize them by 0.`Step 3:`

Use modulo operator(`%`

) to find last digit.`Step 4:`

Use either while loop and division operator (`/`

) or `log()`

and `pow()`

methods of `Math`

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.

`Step 5:`

Display the result.

### Using while loop

It is easy to use modulo operator that will return the last digit of the number, and we can use while loop and division operator to get first digit of number.

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public class Main { public static void main(String args[]) { int number = 502356997; int firstDigit = 0; int lastDigit = 0; lastDigit = number%10; System.out.println("Last digit: "+lastDigit); while(number!=0) { firstDigit = number%10; number /= 10; } System.out.println("First digit: "+firstDigit); } } |

Output

First digit: 5

### Using log() and pow() methods

If we want to use `built-in methods`

like log() and pow() of Math class, then we can use `log()`

method to get the number of digits and `pow()`

method to get divisor value that later on used to get the first digit of number. See the example below.

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public class Main { public static void main(String args[]) { int number = 502356997; int firstDigit = 0; int lastDigit = 0; // find last digit lastDigit = number%10; System.out.println("Last digit: "+lastDigit); int digits = (int)(Math.log10(number)); // Find first digit firstDigit = (int)(number / (int)(Math.pow(10, digits))); System.out.println("First digit: "+firstDigit); } } |

Output

First digit: 5

### Using while loop and pow() method

If we don’t want to use `log()`

method then use while loop to count the number of digits and use that count into the pow() method to get divisor. See the example below.

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public class Main { public static void main(String args[]) { int number = 502356997; int firstDigit = 0; int lastDigit = 0; int count = 0; lastDigit = number%10; System.out.println("Last digit: "+lastDigit); int n = number; while(n!=0) { count++; n = n/10; } firstDigit = number/(int)Math.pow(10, count-1); System.out.println("First digit: "+firstDigit); } } |

Output:

First digit: 5

That’s all about Java program to find first and last digit of number in java.