四つ

1. Origins, structure, and basic meaning

• Structure: 四つ (よっつ) is a native Japanese numeral expressing a count of four.
• Basic usage: 箱が四つ並ぶ counts four boxes, while 四つの皿に分ける modifies the number of plates among which apples are divided.

2. Common pitfalls and similar expressions

• Standalone quantity and noun modifier
  • 箱が四つ places quantity in the predicate, whereas 四つの皿 uses の to modify a noun. The form means neither the written digit nor fourth in sequence.