For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Your body is creating and killing about 2.4 million red blood cells per second.
17
Every year your body replaces 98% of your atoms.
119
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The human brain doesn't stop developing until about 25 years old.
102
The human brain uses approximately as much energy as a 10 watt light bulb.
120
One human hair can support 3 ounces.
191