Remove-Last-Digit Number Pattern in PHP

What You’ll Learn

This pattern prints a number, then repeatedly removes the last digit with integer division by 10. Starting from 86523: 86523, 8652, 865, 86, 8. A single while loop handles it — no nested loops needed. This tutorial covers the loop logic, live preview, worked PHP examples, edge cases, and O(d) complexity.

📝 Problem & Approach

Given starting number $num = 86523, print each value as you remove the last digit until the number becomes zero.

// $num = 86523 (conceptual output)
// 86523
// 8652
// 865
// 86
// 8

Inputs & Outputs

Minimal workflow

while $num != 0:
    echo $num
    $num = intdiv($num, 10)

Approach comparison

🔮 Live Preview

Enter a starting number and see each digit-removal line in the browser.

Press "Draw pattern".

Examples Gallery

Three complete PHP programs — fixed $num = 86523, fgets(STDIN) input, and a string-substr variant. Click View Output to reveal sample console results.

<?php
$num = 86523;

while ($num != 0) {
    echo $num . PHP_EOL;
    $num = intdiv($num, 10);
}

86523
8652
865
86
8

<?php
echo "Enter a number: ";
$input = trim(fgets(STDIN));
if (!is_numeric($input)) {
    echo "Invalid input." . PHP_EOL;
    exit(1);
}
$num = (int) $input;

while ($num != 0) {
    echo $num . PHP_EOL;
    $num = intdiv($num, 10);
}

Enter a number: 86523
86523
8652
865
86
8

<?php
$num = 86523;
$s = (string) $num;

for ($len = strlen($s); $len >= 1; $len--) {
    echo substr($s, 0, $len) . PHP_EOL;
}

86523
8652
865
86
8

🔎 Worked Walkthrough — $num = 86523

Trace each loop iteration: print, then divide by 10.

Zero is never printed because the loop condition is checked before the next iteration.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

💡 Best Practices