Ruler is a ruler or measuring device and drawing tools to draw straight lines. There are various kinds ruler, from straight up to the triangle (usually right-angled triangle isosceles and right-angled triangle 30 ° -60 °). The ruler can be made of plastic, metal, ribbon-shaped and so on. There is also a ruler that can be folded.
The ruler was first used by the people of the Indus valley civilization in 1500 BC. These gauges are made of ivory were found during the excavation. The first ruler has shown amazing accuracy because there is a measure of the decimal in it.
Experts say that the ancient ruler found by the people of the Indus Valley Civilization around 1500 BC, but some others say had already found evidence in the region Lothal (from the time of 2400 BC).
There are also other literature that says that, ruler diitemukan by an Englishman named Napier in the form of slide-rules, first made in England in 1632.
In modern times, people use a folding ruler found by Anton Ullrich in 1851
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