Multiplication was and still is indicated by placing the quantities to be multiplied side by side (juxtaposition), separated by some type of grouping symbol, like parentheses, if necessary. For example, x multiplied by 2 is simply 2x. This is essentially how the Greeks did this only their symbol for 2 was placed behind their symbol for an unknown like x.
The Hindus used the word bha, the first syllable of the word bhavita, meaning "the product," after the factors to be multiplied to indicate multiplication.
Today elementary school students use the symbol × for multiplication. William Oughtred (1574-1660), a clergyman who gave free private lessons to pupils interested in mathematics, used the symbol × for multiplication. He also invented 150 other symbols. The × symbol was not readily accepted though. Gottfried Wilhelm Leibniz (1646-1716) thought it resembled the unknown x too much.
Thomas Harriot (1560-1621) used the dot (·) for multiplication. This was not used much either until Leibniz adopted it. Leibniz also used the cap symbol for multiplication. Today this symbol is used to indicate intersection in set theory.