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Code Mathematics

Find last digit of a number

The given problem is to find the last digit of a given number. The code is implemented in Java and uses simple arithmetic operations to determine the last digit of the number, regardless of its sign (positive or negative).

Problem Statement

We want to find the last digit of a given number, whether it is positive or negative.

Explanation with Example

Let's consider the number 7452 as an example. In the code, we call the function lastDigit(7452). The function starts by taking the absolute value of the input number using the absValue function. This step ensures that we can correctly find the last digit of both positive and negative numbers.

Next, we find the last digit by performing the modulo operation (%) with 10 on the absolute value of the input number. The modulo operation returns the remainder after dividing the number by 10, which happens to be the last digit of the number.

Pseudocode

function absValue(num):
    if num is less than 0:
        return -num
    return num

function lastDigit(num):
    v = absValue(num)
    result = v % 10
    print("Given Number: " + num)
    print("Last Digit: " + result)

Algorithm Explanation

  1. The function absValue(num) takes a number num as input and returns its absolute value by checking if it's negative. If it is, it returns the negation of the number, otherwise, it returns the number itself.

  2. The function lastDigit(num) takes a number num as input and first finds the absolute value of the number by calling the absValue function.

  3. The function then calculates the last digit of the absolute value of the input number by performing the modulo operation with 10 (v % 10). The result is stored in the variable result.

  4. The function prints the original given number and the last digit.

Code Solution

Here given code implementation process.

// Java program for
// Find last digit of a number
public class Digits
{
	public int absValue(int num)
	{
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	public void lastDigit(int num)
	{
		// Get absolute value
		int v = absValue(num);
		// Find last digit
		int result = v % 10;
		// Display given number
		System.out.println("\n Given Number : " + num);
		// Display last digit
		System.out.println(" Last Digit : " + result);
	}
	public static void main(String[] args)
	{
		Digits task = new Digits();
		// Test
		task.lastDigit(7452);
		task.lastDigit(1633);
		task.lastDigit(-8);
		task.lastDigit(348952);
	}
}

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2
// C Program
// Find last digit of a number
// In constant time
#include <stdio.h>

int absValue(int num)
{
	if (num < 0)
	{
		return -num;
	}
	return num;
}
void lastDigit(int num)
{
	// Get absolute value
	int v = absValue(num);
	// Find last digit
	int result = v % 10;
	// Display given number
	printf("\n Given Number : %d", num);
	// Display last digit
	printf("\n Last Digit  : %d\n", result);
}
int main()
{
	// Test
	lastDigit(7452);
	lastDigit(1633);
	lastDigit(-8);
	lastDigit(348952);
	return 0;
}

Output

 Given Number : 7452
 Last Digit  : 2

 Given Number : 1633
 Last Digit  : 3

 Given Number : -8
 Last Digit  : 8

 Given Number : 348952
 Last Digit  : 2
// Include header file
#include <iostream>
using namespace std;
// C++ program for
// Find last digit of a number
class Digits
{
	public: int absValue(int num)
	{
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	void lastDigit(int num)
	{
		// Get absolute value
		int v = this->absValue(num);
		// Find last digit
		int result = v % 10;
		// Display given number
		cout << "\n Given Number : " << num << endl;
		// Display last digit
		cout << " Last Digit : " << result << endl;
	}
};
int main()
{
	Digits *task = new Digits();
	// Test
	task->lastDigit(7452);
	task->lastDigit(1633);
	task->lastDigit(-8);
	task->lastDigit(348952);
	return 0;
}

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2
package main
import "fmt"
// Go program for
// Find last digit of a number
type Digits struct {}
func getDigits() * Digits {
	var me *Digits = &Digits {}
	return me
}
func(this Digits) absValue(num int) int {
	if num < 0 {
		return -num
	}
	return num
}
func(this Digits) lastDigit(num int) {
	// Get absolute value
	var v int = this.absValue(num)
	// Find last digit
	var result int = v % 10
	// Display given number
	fmt.Println("\n Given Number : ", num)
	// Display last digit
	fmt.Println(" Last Digit : ", result)
}
func main() {
	var task * Digits = getDigits()
	// Test
	task.lastDigit(7452)
	task.lastDigit(1633)
	task.lastDigit(-8)
	task.lastDigit(348952)
}

Output

 Given Number : 7452
 Last Digit  : 2

 Given Number : 1633
 Last Digit  : 3

 Given Number : -8
 Last Digit  : 8

 Given Number : 348952
 Last Digit  : 2
// Include namespace system
using System;
// Csharp program for
// Find last digit of a number
public class Digits
{
	public int absValue(int num)
	{
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	public void lastDigit(int num)
	{
		// Get absolute value
		int v = this.absValue(num);
		// Find last digit
		int result = v % 10;
		// Display given number
		Console.WriteLine("\n Given Number : " + num);
		// Display last digit
		Console.WriteLine(" Last Digit : " + result);
	}
	public static void Main(String[] args)
	{
		Digits task = new Digits();
		// Test
		task.lastDigit(7452);
		task.lastDigit(1633);
		task.lastDigit(-8);
		task.lastDigit(348952);
	}
}

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2
<?php
// Php program for
// Find last digit of a number
class Digits
{
	public	function absValue($num)
	{
		if ($num < 0)
		{
			return -$num;
		}
		return $num;
	}
	public	function lastDigit($num)
	{
		// Get absolute value
		$v = $this->absValue($num);
		// Find last digit
		$result = $v % 10;
		// Display given number
		echo("\n Given Number : ".$num.
			"\n");
		// Display last digit
		echo(" Last Digit : ".$result.
			"\n");
	}
}

function main()
{
	$task = new Digits();
	// Test
	$task->lastDigit(7452);
	$task->lastDigit(1633);
	$task->lastDigit(-8);
	$task->lastDigit(348952);
}
main();

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2
// Node JS program for
// Find last digit of a number
class Digits
{
	absValue(num)
	{
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	lastDigit(num)
	{
		// Get absolute value
		var v = this.absValue(num);
		// Find last digit
		var result = v % 10;
		// Display given number
		console.log("\n Given Number : " + num);
		// Display last digit
		console.log(" Last Digit : " + result);
	}
}

function main()
{
	var task = new Digits();
	// Test
	task.lastDigit(7452);
	task.lastDigit(1633);
	task.lastDigit(-8);
	task.lastDigit(348952);
}
main();

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2
#  Python 3 program for
#  Find last digit of a number
class Digits :
	def absValue(self, num) :
		if (num < 0) :
			return -num
		
		return num
	
	def lastDigit(self, num) :
		#  Get absolute value
		v = self.absValue(num)
		#  Find last digit
		result = v % 10
		#  Display given number
		print("\n Given Number : ", num)
		#  Display last digit
		print(" Last Digit : ", result)
	

def main() :
	task = Digits()
	#  Test
	task.lastDigit(7452)
	task.lastDigit(1633)
	task.lastDigit(-8)
	task.lastDigit(348952)

if __name__ == "__main__": main()

Output

 Given Number :  7452
 Last Digit :  2

 Given Number :  1633
 Last Digit :  3

 Given Number :  -8
 Last Digit :  8

 Given Number :  348952
 Last Digit :  2
#  Ruby program for
#  Find last digit of a number
class Digits 
	def absValue(num) 
		if (num < 0) 
			return -num
		end

		return num
	end

	def lastDigit(num) 
		#  Get absolute value
		v = self.absValue(num)
		#  Find last digit
		result = v % 10
		#  Display given number
		print("\n Given Number : ", num, "\n")
		#  Display last digit
		print(" Last Digit : ", result, "\n")
	end

end

def main() 
	task = Digits.new()
	#  Test
	task.lastDigit(7452)
	task.lastDigit(1633)
	task.lastDigit(-8)
	task.lastDigit(348952)
end

main()

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2

// Scala program for
// Find last digit of a number
class Digits()
{
	def absValue(num: Int): Int = {
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	def lastDigit(num: Int): Unit = {
		// Get absolute value
		var v: Int = absValue(num);
		// Find last digit
		var result: Int = v % 10;
		// Display given number
		println("\n Given Number : " + num);
		// Display last digit
		println(" Last Digit : " + result);
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var task: Digits = new Digits();
		// Test
		task.lastDigit(7452);
		task.lastDigit(1633);
		task.lastDigit(-8);
		task.lastDigit(348952);
	}
}

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2
// Swift 4 program for
// Find last digit of a number
class Digits
{
	func absValue(_ num: Int) -> Int
	{
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	func lastDigit(_ num: Int)
	{
		// Get absolute value
		let v: Int = self.absValue(num);
		// Find last digit
		let result: Int = v % 10;
		// Display given number
		print("\n Given Number : ", num);
		// Display last digit
		print(" Last Digit : ", result);
	}
}
func main()
{
	let task: Digits = Digits();
	// Test
	task.lastDigit(7452);
	task.lastDigit(1633);
	task.lastDigit(-8);
	task.lastDigit(348952);
}
main();

Output

 Given Number :  7452
 Last Digit :  2

 Given Number :  1633
 Last Digit :  3

 Given Number :  -8
 Last Digit :  8

 Given Number :  348952
 Last Digit :  2
// Kotlin program for
// Find last digit of a number
class Digits
{
	fun absValue(num: Int): Int
	{
		if (num < 0)
		{
			return -num;
		}
		return num;
	}
	fun lastDigit(num: Int): Unit
	{
		// Get absolute value
		val v: Int = this.absValue(num);
		// Find last digit
		val result: Int = v % 10;
		// Display given number
		println("\n Given Number : " + num);
		// Display last digit
		println(" Last Digit : " + result);
	}
}
fun main(args: Array < String > ): Unit
{
	val task: Digits = Digits();
	// Test
	task.lastDigit(7452);
	task.lastDigit(1633);
	task.lastDigit(-8);
	task.lastDigit(348952);
}

Output

 Given Number : 7452
 Last Digit : 2

 Given Number : 1633
 Last Digit : 3

 Given Number : -8
 Last Digit : 8

 Given Number : 348952
 Last Digit : 2

Resultant Output Explanation

For the given code, the output is as follows:

Given Number: 7452
Last Digit: 2

Given Number: 1633
Last Digit: 3

Given Number: -8
Last Digit: 8

Given Number: 348952
Last Digit: 2
  • For the number 7452, the last digit is 2.
  • For the number 1633, the last digit is 3.
  • For the number -8, the last digit is 8.
  • For the number 348952, the last digit is 2.

Time Complexity

The time complexity of the code is constant O(1) because the operations performed (absolute value and modulo) are constant time operations, irrespective of the size of the input number. The code performs a fixed number of operations to determine the last digit, so the time complexity remains constant.

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