Claude Opus 4.8 vs GPT-5.5 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…

Adjusted bank statement balance:

- Bank statement closing balance: **£8,412.55**
- Less unpresented cheque: **£120.00**
- Add lodgement not yet credited: **£120.00**

These cancel, so adjusted bank balance remains **£8,412.55**.

Cash book balance: **£8,376.55**

So the difference is:

**£8,412.55 − £8,376.55 = £36.00**

The bank is **£36.00 higher** than the cash book.

This is the classic sign of a **transposition error**: **£451** and **£415** have been interchanged.

Arithmetic rule: a transposition error is usually divisible by **9**. Her…