Why your bank reconciliation is out — and which entry did it
Why won't my bank reconciliation balance?
On the example here your records are $720.00 higher than the statement once deposits in transit and outstanding payments are taken into account — and that difference is not random. It divides by nine, which is what happens when two adjacent digits are swapped, and one of the entries explains it exactly. Every candidate below carries the amount and the arithmetic that proves it.
Any currency — the arithmetic is the same everywhere · amounts are shown in US dollars · single account · one period · nothing you type is stored or sent
Every reconciliation template ends the same way: a difference, and the advice to check again. But the difference is not silent. Each kind of mistake leaves an arithmetic signature in the number itself, and that signature can be read.
Your two balances
Separate them with commas, spaces or new lines. They are what make a proof possible: without them the difference can only be given a class, not a culprit. Nothing here leaves your browser.
What the difference says
The difference divides by nine, which is what happens when two adjacent digits are swapped. $1,198.75 keyed as $1,918.75 moves the balance by exactly $720.00.
- Open that entry and compare it digit by digit with the source document. The eye reads the amount as a whole and slides straight past a swap.
- It does not read your bank statement or your books — you enter the figures.
- It finds one signature at a time. Two errors that overlap can hide each other, and the tool says so rather than guessing.
- It does not check whether a transaction should exist, only whether the arithmetic of the difference has a known shape.
- It is not tied to any country's accounting rules; the arithmetic is the same everywhere.
The tests are arithmetic, not opinion, and the page proves each one: a swap of two adjacent digits always moves a number by a multiple of nine, an amount posted on the wrong side always moves a balance by twice itself, and a decimal point one place out always moves it by nine times the smaller of the two amounts. Our own verification runs every one of those claims against the shipped code before the page goes out.
This is arithmetic, not an audit. It narrows the search; it does not certify your books.
Want the entries ready before you go looking?
This page can only prove what you can list. The bookkeeping spreadsheet keeps income, expenses, mileage, invoices and inventory as you go, so the amounts for a period are already in one place when a difference appears. It is built for United States sole proprietors and maps every category to its Schedule C line; the reconciliation arithmetic above is the same in any country.
Small Business Bookkeeping Spreadsheet — $14.99Questions people actually ask
Why does a difference that divides by nine mean a transposition?
Because swapping two adjacent digits changes a number by nine times the difference between them, scaled by where they sit. Write fifty-four where you meant forty-five and the value moves by nine; write five hundred and forty where you meant four hundred and fifty and it moves by ninety. The nine never goes away, which is why the test is reliable — and why it also catches a misplaced decimal point, where the same nine turns up for the same reason.
The difference is exactly twice one of my entries. What does that mean?
An amount was almost certainly posted on the wrong side. If money going out is recorded as money coming in, the balance is wrong twice over: once for the subtraction that never happened, and again for the addition that should never have been there. That is why halving the difference so often finds the culprit immediately.
Nothing matches. What now?
Then the difference is probably not inside this period at all. Check the opening balance first: if the previous period was already out, every hour spent on this month's entries is wasted. After that, look for a whole transaction on the statement that is not in your records — a direct debit, a card fee, a transfer between your own accounts.
Does the tool see my figures?
No. The arithmetic runs in your browser, nothing is sent anywhere and nothing is stored. Close the tab and it is gone.
Can two errors happen at once?
Yes, and it is the honest weakness of every signature test. Two mistakes can partly cancel, leaving a difference whose shape belongs to neither. When nothing fits, that is one of the things it means, and the page says so instead of picking the nearest answer.
