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The prime symbol ( ′ ), double prime symbol ( ″ ), triple prime symbol ( (unicode:‴) ), quadruple prime symbol ( (unicode:⁗) ) etc., are used to designate several different units and for various other purposes in mathematics, the sciences, linguistics and music. The prime symbol should not be confused with the apostrophe, single quotation mark, acute accent, or grave accent; the double prime symbol should not be confused with the double quotation mark, the ditto mark, or the letter double apostrophe. The prime symbol is very similar to the Hebrew geresh, but in modern fonts the geresh is designed to be aligned with the Hebrew letters and the prime symbol not, so they should not be interchanged. ==Designation of units== The prime symbol (′) is commonly used to represent feet (ft), arcminutes (am), and minutes (min). However, for convenience, a (') (single quote mark) is commonly used. The double prime (″) represents inches (in), arcseconds (as), and seconds (s). However, for convenience, a (") (double quotation mark) is commonly used. Thus, 3′ 5″ could mean 3 feet and 5 inches (of length) or 3 minutes and 5 seconds (of time). As an angular measurement, 3° 5′ 30″ means 3 degrees, 5 arcminutes and 30 arcseconds. The triple prime ((unicode:‴)) in watchmaking represents a ligne. It is also occasionally found in historical astronomical works to denote thirds ( of a second of arc〔E.g., in 〕). Likewise, a quadruple prime ((unicode:⁗)) denotes fourths ( of a third, a convention already used by Jamshīd al-Kāshī. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Prime (symbol)」の詳細全文を読む スポンサード リンク
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