The human brain doesn't stop developing until about 25 years old.
102
Your body is creating and killing about 2.4 million red blood cells per second.
17
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Your thumb is about the same size as your nose.
124
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197