Remove Last Digit Number Pattern in JavaScript

What You’ll Learn

Program 60 prints a shrinking number pattern: start with an integer, print it, then remove the last digit with Math.floor(num / 10) until the value reaches zero. This tutorial covers the while-loop core, integer division, a live preview, worked JavaScript examples, edge cases, and O(d) complexity.

📝 Problem & Approach

Given starting integer num = 86523, print the number on each line while removing the last digit until num becomes 0.

// num = 86523
//86523
//8652
//865
//86
//8

Inputs & Outputs

Minimal workflow

while num is not 0:
    log num
    num = floor(num / 10)

Approach comparison

🔮 Live Preview

Enter a positive integer between 10 and 99999999 and draw the digit-removal pattern in the browser.

Press "Draw pattern".

Examples Gallery

Three complete JavaScript programs — fixed starting value, user input with negative handling, and a compact num = 123 trace. Click View Output to reveal sample console results.

let num = 86523;

while (num !== 0) {
  console.log(num);
  num = Math.floor(num / 10);
}

86523
8652
865
86
8

const numInput = prompt("Enter a number:");
const parsed = parseInt(numInput, 10);

if (!Number.isFinite(parsed)) {
  console.log("Please enter a valid integer.");
} else {
  let num = Math.abs(parsed);

  while (num !== 0) {
    console.log(num);
    num = Math.floor(num / 10);
  }
}

Enter a number: 86523
86523
8652
865
86
8

let num = 123;

while (num !== 0) {
  console.log(num);
  num = Math.floor(num / 10);
}

123
12
1

🔎 Worked Walkthrough — num = 86523

Trace each loop iteration: print the current num, then apply integer division by 10.

Total lines printed: 5 = digit count of the starting number.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

💡 Best Practices