C# Number Pattern (Remove Last Digit)

What Is This Pattern?

A remove-last-digit pattern prints an integer, then repeatedly strips the rightmost digit with integer division by 10 until the value becomes zero.

Rule: while num != 0 → print num → num = num / 10

86523
8652
865
86
8     ← start = 86523

Follows the hollow square border in Program 59; next is the growing reverse pattern in Program 61.

How to Solve It

Use a while loop: print the current value, then divide by 10. Stop when num reaches 0.

Pseudocode

while num is not 0:
    print num
    num = num / 10

Cheat sheet

Write vs WriteLine

Unlike nested triangle patterns, each iteration needs its own newline — so use WriteLine(num) every step.

Live Preview

Change the starting number and the digit-removal pattern updates instantly — absolute value, up to 9 digits.

86523
8652
865
86
8

Worked Walkthrough — num = 86523

Trace each print-then-divide step until the loop stops.

Five digits → five lines → O(d) time. Integer division truncates toward zero, so no floating-point is involved.

C# Programs

Three complete programs: fixed num = 86523, TryParse input, and a compact num = 123 demo. Use View Output to reveal sample results.

using System;

class Program
{
    static void Main()
    {
        int num = 86523;

        while (num != 0)
        {
            Console.WriteLine(num);
            num = num / 10;
        }
    }
}

86523
8652
865
86
8

using System;

class Program
{
    static void Main()
    {
        Console.Write("Enter a number: ");
        if (!int.TryParse(Console.ReadLine(), out int num))
        {
            Console.WriteLine("Please enter a valid integer.");
            return;
        }

        num = Math.Abs(num);

        while (num != 0)
        {
            Console.WriteLine(num);
            num /= 10;
        }
    }
}

Enter a number: 120
120
12
1

using System;

class Program
{
    static void Main()
    {
        int num = 123;

        while (num != 0)
        {
            Console.WriteLine(num);
            num /= 10;
        }
    }
}

123
12
1

Time and Space Complexity

Each iteration removes one digit, so the loop runs d times for a d-digit start — linear in digit count, constant extra memory.

Key Takeaways