Decrement Integer Digits

Wraparound (default): each digit is treated independently. 0 − 1 wraps to 9, regardless of neighbors. 100 − 1-each-digit becomes 099 (or just 99 depending on display). Useful for ciphers, digit permutations, and demonstrating mod-10 arithmetic.

Same counter (underflows) but different meaning in each mode: in wraparound, it’s “how many digits wrapped past 0” (data preserved via mod, just visualized differently); in borrow, it’s “how many integers went negative” (sign flipped); in clamp, it’s “how many digits were saturated at 0 or 9” (data lost via clamping). The label updates with the mode so the meaning matches.

Negative decrement = ADD. The math is symmetric: x − (−1) = x + 1. So decrement value = −3 in wraparound mode shifts each digit UP by 3 with wraparound at 9 → 0. Useful for symmetric calculations and undoing decrements without switching tools. The “Negative dec adds” sample demonstrates.

Sign preserved, digits decremented on absolute value. -542 with decrement 1 in wraparound → -431. The leading minus sign is treated as metadata, not a digit. In borrow mode, if the digit-result goes negative, the sign FLIPS: -543 with decrement 9 each digit (= subtract 999) → −543 − 999 = −1542, but if we think of it as |543| − 999 = −456, with the input’s negative sign, you get −(−456) = 456 → wait, this is getting confusing. In practice the tool’s borrow mode does: take absolute value, do subtraction, if result is negative, flip the input sign. Use wraparound or clamp for cleaner semantics on negatives.

Wraparound mode preserves them as strings: 100 − 1-each-digit wraparound = 099. Borrow mode strips leading zeros (treats result as a number): 100 − 1-each-digit borrow = 89 (since 100 − 11 = 89). For digit-puzzle use cases (where you care about the per-digit visualization), use wraparound; for arithmetic use cases, use borrow.

Tested at 100k integers under 250ms on a typical desktop. The bottleneck is browser DOM update for the output textarea, not the math.

Newlines, commas, or semicolons as separators (any combination). Only strict integer tokens are processed – fractional like 3.14 or non-numeric like foo are silently skipped (count is shown in the diagnostic if non-zero). Negative integers must use a leading minus, not surrounded by parentheses or postfixed.

Number puzzles and ciphers where each digit position matters independently. Generating sequences with predictable per-digit relationships (e.g., 123 → 234 → 345). Demonstrating modular arithmetic to students. Sanitizing IDs by clamping out-of-range digit modifications. Round-tripping with the companion “Increment Integer Digits” tool to verify reversibility.

Yes. All processing happens in your browser using vanilla JavaScript. Integers never leave your device. Download is generated in-memory and offered locally.