Errors Updated November 2026

Transposition error

A transposition error happens when two adjacent digits are swapped while recording an amount, such as writing 450 instead of 540. The resulting difference (90 here) is always divisible by 9, so if a reconciliation is off by a multiple of 9, look for swapped digits first.

Syntax

Test: (Adjusted bank - Adjusted book) mod 9 = 0 suggests a transposition or a slide

Part	What it is
`Transposition`	Digits swapped: 540 vs 450, difference 90
`Slide`	Decimal moved: 540 vs 54.00, difference 486, also divisible by 9
`Correction`	Adjust the book side by the difference; post the difference

Examples

Check written 540, recorded 450

Result: Difference 90; 90 / 9 = 10. Books deducted too little: subtract 90 on the book side. Entry: Dr Accounts Payable 90 / Cr Cash 90.

Deposit of 1,230 recorded as 1,320

Result: Difference 90; books too high. Subtract 90 on the book side. Entry: Dr Accounts Receivable 90 / Cr Cash 90.

Reconciliation difference 63

Result: 63 / 9 = 7, so check for a swap such as 81 vs 18 or 92 vs 29 in the register.

Common mistakes

Assuming every multiple of 9 is a transposition: it is a hint, not proof; confirm against the source document.
Fixing the digits in the ledger by editing the original entry after the period is closed: post a correcting entry instead.
Ignoring a difference not divisible by 9: it could still be two errors that net to an odd figure.

Practice Transposition error

These drills check your answer on live data, free, no account needed.

Digits swapped in the booksClassify every line, enter the correction for any error, then the adjusted bank and book balances.
Correcting a book errorClassify every line, enter both adjusted balances, then choose the journal entry the company must record for each item that affects its books.

Questions

Why is a transposition error always divisible by 9?

Swapping digits in positions with place values a and b changes the number by (digit difference) x (a - b), and every difference of place values (90, 900, 9, ...) is a multiple of 9.

What is the difference between a transposition and a slide?

A transposition swaps digits (540 to 450). A slide shifts the decimal point (540 to 54). Both give differences divisible by 9.

Book errorsA book error is a company mistake in recording cash: a check entered for the wrong amount or a deposit recorded twice. Adjust the book side and correct it.
Reconciliation does not balanceWhen the adjusted bank and book balances differ, the difference tells you where to look: divisible by 9 means a transposition, twice an item means a sign.
Correcting entryA correcting entry fixes a mistake in a posted transaction: reverse the wrong part and record the right one, or post the net difference. Examples by error.