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Although the Roman numeral for the number 4 has always been taught to have been "IV," according to historians, the ancient Romans probably used "IIII" most of the time. This is partially backed up by the fact that early grandfather clocks displayed IIII for the number 4 instead of IV. Early clockmakers apparently thought that the IIII balanced out the VIII (used for the number 8) on the clock face and that it just looked better.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
Increased intake of vitamin D has been shown to reduce fractures up to 25% in older people.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
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