Question 1
Question 2
Ask unlimited questions for free
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
For a complete list of videos, visit our video library