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There used to be a metric calendar, as well as metric clocks. The metric calendar, or "French Republican Calendar" divided the year into 12 months, but each month was divided into three 10-day weeks. Each day had 10 decimal hours. Each hour had 100 decimal minutes. Due to lack of popularity, the metric clocks and calendars were ended in 1795, three years after they had been first marketed.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
The familiar sounds of your heart are made by the heart's valves as they open and close.