Claude Opus 4.8 vs GPT-5.3-Codex for bookkeeping

# Bank Reconciliation Error Analysis

## The Difference

£8,412.55 − £8,376.55 = **£36.00**

## Finding the Error

Comparing the cash book receipts with the bank credits:

| Cash book | Bank statement |
|-----------|----------------|
| £451.00 | £415.00 |
| £1,208.30 | £1,208.30 |
| £96.75 | £96.75 |
| £2,340.00 | £2,340.00 |
| £415.00 | £451.00 |
| £188.50 | £188.50 |

The figures **£451.00** and **£415.00** appear in *reversed order*. The digits 5 and 1 have been swapped: £4**51** became £4**15**.

## Kind of Error

This is a **transposition…

You have an **unexplained difference of £36.00**:

\[
£8,412.55 - £8,376.55 = £36.00
\]

The £120 unpresented cheque and £120 lodgement cancel out, so they are **not** the cause.

### What kind of error this is
This is the classic pattern of a **transposition error** (digits swapped), e.g. **£451** vs **£415**.

\[
451 - 415 = 36
\]

### The quick arithmetic rule
If a reconciliation difference is divisible by **9**, suspect a transposition or similar digit error.

\[
36 \div 9 = 4 \text{ exactly}
\]

So £36 immediately points to that class of e…