Number Pattern by Removing Last Digit in C++

Beginner
⏱️ 5 min read
📚 Updated: Aug 2025
🎯 2 Code Examples
While Loop
Number pattern output in C++ by removing last digit (86523, 8652, 865, 86, 8)

What You’ll Learn

How to print a number pattern by repeatedly removing the last digit of an integer in C++.

This uses a simple while loop plus integer division: num = num / 10.

⭐ Pattern Output

For num = 86523, the output looks like this:

Output
86523
8652
865
86
8
1

Complete C++ Program

We print the current number, then remove the last digit by dividing by 10 until the number becomes 0.

C++
#include <iostream>
using namespace std;

int main() {
    int num = 86523;

    while (num != 0) {
        cout << num << "\n";
        num = num / 10;
    }

    return 0;
}

🧠 How It Works

1

Start with a number

int num = 86523; is the value we want to shorten step by step.

Setup
2

Loop until it becomes 0

while (num != 0) keeps running as long as there is at least one digit left.

Loop
3

Print then remove last digit

We print num, then update it with num = num / 10, which removes the last digit via integer division.

Digit trim
4

Stop naturally

Eventually, dividing by 10 makes the value 0, the condition fails, and the loop ends.

Finish
=

Digit-removal pattern

If the number has d digits, the loop runs d times, so the time complexity is O(d).

2

Variation — User Input Version

Read a number from the user and print the same digit-removal pattern.

C++
#include <iostream>
using namespace std;

int main() {
    long long num;

    cout << "Enter a number: ";
    cin >> num;

    if (num == 0) {
        cout << 0 << "\n";
        return 0;
    }

    if (num < 0) num = -num;

    while (num != 0) {
        cout << num << "\n";
        num /= 10;
    }

    return 0;
}

💡 Tips for Enhancement

Try These

  • Print the removed digit each step using num % 10
  • Count how many steps were printed (digit count)
  • Extend it to print prefixes left-to-right using strings
  • Handle negative values by printing the sign separately
  • Validate input with cin.fail() for robustness

Avoid

  • Using floating-point division (you want integer division)
  • Forgetting to update num inside the loop
  • Printing with endl in tight loops (slower)
  • Ignoring the num == 0 case if you want 0 printed

Key Takeaways

1

Integer division by 10 removes the last digit of a number.

2

A while loop is ideal when you don’t know the number of steps in advance.

3

The number of printed lines equals the number of digits, so complexity is O(d).

4

This digit logic is also useful for reversing numbers and digit-sum problems.

❓ Frequently Asked Questions

Because each step removes one digit. Once the number becomes a single digit, dividing by 10 makes it 0 and the loop ends.
Yes. The removed digit is num % 10 before doing num /= 10.
The loop would not run, so if you want something printed, handle it explicitly by printing 0 once.
O(d), where d is the number of digits in the number.

Explore More C++ Number Patterns!

Keep practicing with loop-based patterns to build strong fundamentals.

All Number Patterns →
Did you know?

Digit trimming is the basis for many classic tasks like reversing a number, checking palindromes, and extracting digits one by one.

About the author

Mari Selvan M P
Mari Selvan M P 🔗

Developer, cloud engineer, and technical writer

  • Experience 12 years building web and cloud systems
  • Focus Full Stack Development, AWS, and Developer Education

I write practical tutorials so students and working developers can learn by doing—from databases and APIs to deployment on AWS.

AWS Certified Developer – Associate (Credly)

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