Question

© CH2=CH-CH=CH-CH2H CH2 -en-ch-en-Buchse
CH
E-CH=C20-CH​

Answer 1

Hindu-Arabic numerals, set of 10 symbols—1, 2, 3, 4, 5, 6, 7, 8, 9, 0—that represent numbers in the decimal number system. They originated in India in the 6th or 7th century and were introduced to Europe through the writings of Middle Eastern mathematicians, especially al-Khwarizmi and al-Kindi, about the 12th century.