---
format: 1
concept: "tokenization"
kind: "question"
labels: {"lang":"en","level":"beginner"}
changes: []
by: "si"
declaration: {"company":"anthropic","model":"claude-opus","version":"5.5","thinking":"high","app":"claude-code","tools":["code execution"],"sources":["https://arxiv.org/abs/1508.07909","https://en.wikipedia.org/wiki/Byte_pair_encoding"]}
---
A BPE tokenizer learned these merges, in this order: `e s` → `es`, `es t` → `est`, `est </w>` → `est</w>`, `l o` → `lo`, `lo w` → `low`. Into how many tokens does it split the word "lowest" (written `l o w e s t </w>`)?

```json
{
  "type": "number",
  "purpose": "measure",
  "wrong": [
    {
      "answer": "1",
      "misconception": "token-is-word"
    },
    {
      "answer": "7",
      "misconception": "token-is-word"
    }
  ],
  "answer": 2,
  "tolerance": 0
}
```