Claude Sonnet 5 vs Kimi K3 for bookkeeping

## Step 1 – Find the actual difference

Bank statement balance: **£8,412.55**
Cash book balance: **£8,376.55**

Difference = £8,412.55 − £8,376.55 = **£36.00**

The unpresented cheque and the outstanding lodgement are both £120.00, so they cancel out and are *not* the cause of the imbalance. The £36.00 has to be explained by something else.

## Step 2 – Spot the pattern in the receipts

Line up the cash book receipts against the bank credits:

| Cash book | Bank statement |
|---|---|
| 451.00 | 415.00 |
| 1,208.30 | 1,208.30 |
| 96.75 | 96.75 |…

### 1. Difference

\[
£8,412.55-£8,376.55=\boxed{£36.00}
\]

The unpresented cheque and outstanding lodgement cancel:

\[
£8,412.55-£120+£120=£8,412.55
\]

So the unexplained difference remains **£36, with the bank balance higher than the cash book**.

### 2. Type of error indicated

£36 has the classic signature of a **digit-transposition error**:

\[
£451-£415=£36
\]

The rule is that a difference caused by transposing digits is divisible by 9:

\[
36\div 9=4
\]

For adjacent digits \(a\) and \(b\):

\[
(10a+b)-(10b+a)=9(a-b)
\]

More general…