Add Errors to Numbers - Modify Numbers So They Are Almost the Same but Contain Errors

Machines and humans both make tiny number mistakes - a digit swapped, a neighbour transposed, a value bumped by one. Adding errors on purpose builds corrupted twins that are almost right but subtly off: the raw material for proofreading drills and test data.

Add Errors to Numbers corrupts your numbers into near-identical copies. Pick the number of errors and copies, mix transposition, substitution, increment and deletion, and every batch number expands into a labelled crop of subtle wrong numbers - copy or download.

• Near-copies: Almost-right corrupted twins per number.
• Four error types: Swap, change, bump, delete.
• Error control: Choose 1-5 errors per copy.
• Copy control: How many corrupt copies to make.
• Labelled output: Each note says which error was injected.
• Batch mode: Up to 1000 numbers per run.

1. Enter numbers - one per line, minimum two digits.
2. Set errors per copy - how many corruptions to inject.
3. Set copies per number - how many near-twins to emit.
4. Generate - each number sprouts corrupted copies.
5. Copy or download - the error-labelled list.

1. 12345 with a swap: 12354 (neighbours 4/5 transposed).

2. 888888 with a change: 888388 (a digit replaced in place).

3. 2020 with an increment: 2021 or 3020 (a digit bumped).

4. 987654 with a deletion: 98754 (one digit vanishes).

5. 149162536 with two errors: e.g. 139172536 (a bump and a swap).

• Typo training: Practice spotting near-miss errors.
• Test data: Realistic corrupted inputs on demand.
• Four corruptions: Mix-and-match error styles.
• Fully controlled: Errors and copies tuned to your drill.
• Labelled: Every error type is on screen.
• Private and free: Everything runs in the browser; nothing is uploaded or logged.