Tech Number in Java: Definition, Rules, Examples, and Practice Problems

A Tech Number is a special number in mathematics and programming where the number must have an even number of digits. If the number is split into two equal halves, the sum of these halves squared should be equal to the original number.

What Is a Tech Number?

A number is called a Tech Number if:

• The number must have an even number of digits.
• Split the number into two equal halves.
• Add both halves.
• Square the sum.
• If the result matches the original number, it is a Tech Number.

Example:

• 2025 → split into 20 and 25
• 20 + 25 = 45
• 45² = 2025 → Tech Number

Why Is It Called a Tech Number?

The name "Tech" is derived from early logical puzzles used in entrance exams for technical institutes. It represents a number property based on digit manipulation and math patterns.

Java Program to Check Tech Number

Below is the Java program to check if a given number is a Tech Number:

import java.util.Scanner;

public class TechNumber {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number: ");
        int num = sc.nextInt();

        String s = String.valueOf(num);

        // must have even number of digits
        if (s.length() % 2 != 0) {
            System.out.println(num + " is NOT a Tech Number");
            return;
        }

        int mid = s.length() / 2;

        int firstHalf = Integer.parseInt(s.substring(0, mid));
        int secondHalf = Integer.parseInt(s.substring(mid));

        int sum = firstHalf + secondHalf;

        if (sum * sum == num) {
            System.out.println(num + " is a Tech Number");
        } else {
            System.out.println(num + " is NOT a Tech Number");
        }
    }
}

Examples

3 Practice Challenges

Challenge 1: Basic Validation

Write a Java program that checks if a number is a Tech Number without converting it to a string.

Challenge 2: List Checker

Given a list of 10 numbers, print only those that are Tech Numbers.

Challenge 3: Range Generator

Write a Java program to find all Tech Numbers between 1 and 1,00,000.