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The longest a person has survived after a heart transplant is 24 years.
It is difficult to obtain enough calcium without consuming milk or other dairy foods.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.
Vaccines prevent between 2.5 and 4 million deaths every year.
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."
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