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Hatch marks, sometimes also called hash marks, or tick marks, are a form of mathematical notation. They are typically used three ways: #Unit and value marks – as on a ruler or number line. #Congruency notation – as on a geometric figure. #Graphed points – as on a graph. Hatch marks are frequently used as an alternate form of abbreviation for some common units of measurement. In regard to distance, a single hatch mark typically indicates feet and a double hash mark indicates inches within the English system. In regard to time, a single hatch mark indicates minutes and a double hatch mark indicates seconds; these typically occur following hours, indicated by an elevated circle. The same system is used within geometry and trigonometry for the measurement of angles in degrees, minutes and seconds. ==Unit and value marks== Every ruler or number line that uses vertical line segments to mark distance values is using unit and value hatch marks. The marks appear as single vertical line segments that are parallel to each other and evenly spaced. This distance between each mark is one unit. Each mark has a value at that location. The length of the segment is usually an indication of the size of the value. For example, longer line segments are usually used for integers (or just natural numbers). Shorter line segments are usually used for fractions. The hatch mark pattern on the ruler or number line gives the viewer a visual clue as to the value at a certain point on the number line, even if all the hatch marks do not have labels. <----|----|----|----|----|----|----|----|----|----|----|----|----|----> -3 -2 -1 0 1 2 This type of usage of hatch marks falls in the range of number theory and geometry. It is here that the term hatch marks is interchangeable with hash marks or tick marks. 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「Hatch mark」の詳細全文を読む スポンサード リンク
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