Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
When you take a step, you are using up to 200 muscles.
886
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Your thumb is about the same size as your nose.
124
The human brain doesn't stop developing until about 25 years old.
102
The human body contains over a billion miles of DNA.
147
The average sperm cell swims at 8 inches per hour.
76
The human brain uses approximately as much energy as a 10 watt light bulb.
120