It takes about 20 seconds for a red blood cell to circle the whole body.
102
One human hair can support 3 ounces.
191
Enamel is hardest substance in the human body.
61
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99