Irregular plural nouns like "child" (children), "foot" (feet), and "tooth" (teeth) defy the standard -s pluralization rule, showcasing the unpredictable nature of number agreement in English grammar; these exceptions require memorization for grammatical accuracy. Numerals themselves can exhibit irregularities. While most cardinal numbers follow predictable patterns, ordinals (like "first," "second," "third") are highly irregular, demonstrating that number agreement extends beyond simple noun-verb relationships and encompasses a broader range of linguistic structures.