Your thumb is about the same size as your nose.
124
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Your body is creating and killing about 2.4 million red blood cells per second.
17
Enamel is hardest substance in the human body.
61
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The human body contains over a billion miles of DNA.
147
Your heart will pump about 212 million liters in its lifetime.
26
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73