What number does the Roman numeral D represent?
Answer500
In Roman numerals, D stands for 500, sitting between C (100) and M (1,000) in the numbering system.
Source: Wikipedia (Roman numerals) (2022) en.wikipedia.org
Language · Facts & sources
D facts & stats
4 sourced facts about the letter D, each with the context behind the number. 4 more are in today's round and appear here after it closes.
The basics
Expert level
About how many people worldwide can be considered vitamin D deficient?
Answerover 1 billion
More than one billion people worldwide — across all ages — can be considered vitamin D deficient, according to health researchers.
Source: Wikipedia (Vitamin D) (2023) en.wikipedia.org
In what year was vitamin D discovered and named?
Answer1922
Vitamin D was discovered and named in 1922 during research into rickets, becoming the fourth vitamin to be identified.
Source: Wikipedia (Vitamin D) (2023) en.wikipedia.org
What share of the U.S. population is Rh D-negative (the '-' in a blood type like O-negative)?
Answerabout 15%
About 15% of the U.S. population is Rh D-negative, compared to roughly 6% of the global population — a gap that varies a lot by ancestry.
Source: Wikipedia (Rh blood group system) (2022) en.wikipedia.org
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