A remove-last-digit pattern prints an integer, then drops its rightmost digit with Math.floor(num / 10), repeating until the value becomes 0.
Rule: print, then num = Math.floor(num / 10)
86523
8652
865
86
8 ← start = 86523Unlike Program 59 (grid border loops), this uses one while loop — line count equals the digit count.
Loop while num !== 0: log the current value, then integer-divide by 10.
| Method | Idea | Best for |
|---|---|---|
| While + divide | Print, then Math.floor(num / 10) | Classic digit-removal demos |
| Compact | Same loop with a smaller start (e.g. 123) | Quick dry-runs |
while num !== 0:
print num
num = floor(num / 10)| Goal | Pattern |
|---|---|
| Loop | while (num !== 0) |
| Print current | console.log(num); |
| Drop last digit | num = Math.floor(num / 10); |
| Negatives | num = Math.abs(parsed); before the loop |
| Lines printed | Digit count of the start value |
| API | Effect | Use for |
|---|---|---|
line += … | Stays on the same row | Not needed here — each step is its own line |
console.log(num) | Ends the current row | Every shrinking value |
Same idea as C# WriteLine: each call prints a full value and moves to the next line.
Change the starting number and the shrinking sequence updates instantly.
Trace num = 86523 — print first, then divide.
| Step | Printed | After Math.floor(num / 10) |
|---|---|---|
| 1 | 86523 | 8652 |
| 2 | 8652 | 865 |
| 3 | 865 | 86 |
| 4 | 86 | 8 |
| 5 | 8 | 0 (loop ends) |
Five digits → five lines. When num becomes 0, the while condition fails.
Three complete programs: fixed 86523, prompt input with Math.abs, and a compact 123 demo. Use View Output for samples, or Try It Yourself to edit and run live.
num = 86523Print, then drop the last digit until the value is zero.
let num = 86523;
while (num !== 0) {
console.log(num);
num = Math.floor(num / 10);
}1. Guard with a while. Keep looping while num is not zero.
2. Print before shrinking. console.log(num) shows the current value on its own line.
3. Drop one digit. Math.floor(num / 10) removes the rightmost digit — five digits means five lines.
Read the start value with prompt, validate, and use Math.abs for negatives.
const parsed = parseInt(prompt("Enter a number:"), 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);
}
}1. Prompt and validate. Reject non-finite parses before entering the loop.
2. Normalize sign. Math.abs lets negative input shrink the same way as positive.
3. Same shrink core. Only the source of num changes — print then divide matches Example 1.
num = 123Same while loop with a smaller start for a quick visual check.
let num = 123;
while (num !== 0) {
console.log(num);
num = Math.floor(num / 10);
}1. Shrink the start. Only the initial num changes — still print then divide.
2. Easier to trace. Three lines — useful while learning Math.floor(num / 10).
3. Same stop rule. The loop ends when the last digit becomes 0 after division.
Check these before calling the solution done.
Always assign num = Math.floor(num / 10)
Forgetting the update leaves num unchanged — infinite loop.
Use Math.floor, not plain /
Plain division keeps decimals (e.g. 865.2) and never reaches exact 0 the same way.
Empty output
The loop body never runs when the start value is already zero.
Validate parseInt
Check Number.isFinite(parsed) before the loop; use Math.abs for negatives.
| Program | Time | Extra space |
|---|---|---|
| Fixed / compact (Examples 1, 3) | O(d) | O(1) |
| User input (Example 2) | O(d) | O(1) |
Each iteration removes one digit — for d digits the loop runs d times.
num, then num = Math.floor(num / 10).while (num !== 0) ends when all digits are gone.console.log is a full shrinking step.O(d) — one step per digit.One line: while the number is nonzero, log it and integer-divide by 10.
Each iteration prints the current number, then num = Math.floor(num / 10) drops the last digit — runtime is O(d) for d digits.
Continue with the next pattern in the JavaScript number-pattern series.
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