Number of bones in adult human (approx).

**The reasoning** The adult human skeleton contains **approximately 206 bones**. This is a fundamental anatomy fact you need to memorize for your exams. Here's the key: babies are actually born with about 270 bones, but as we grow, many bones **fuse together**. For example, the skull bones merge, and bones in the spine join up. By the time you're an adult (around 20-25 years old), you're left with roughly 206 bones. The breakdown: skull (~22), spine (~26), ribs and sternum (~25), arms (~60), legs (~60), plus smaller bones in hands and feet. **Why the wrong options tempt you** - **100** is too low — that's barely half! Students might confuse this with major bone groups. - **150** sounds "reasonable" if you're just guessing somewhere in the middle. - **300** catches people who remember babies have more bones but forget about the fusion process as we mature. **Quick takeaway** Remember: **"Born with 270, grow to 206"** — bones fuse as you mature, leaving adults with approximately 206 bones.