Metrication, or the conversion to a measurement system based on the International System of Units (SI), occurred in India in stages between 1955 and 1962. The metric system in weights and measures was adopted by the Indian Parliament in December 1956 with the Standards of Weights and Measures Act, which took effect beginning 1 October 1958. The Indian Coinage Act was passed in 1955 by the Government of India to introduce decimal coinage in the country. The new system of coins became legal tender in April 1957, where the rupee consists of 100 paise. For the next five years, both the old and new systems were legal. In April 1962, all other systems were banned. This process of metrication is called "big-bang" route, which is to simultaneously outlaw the use of pre-metric measurement, metricate, reissue all government publications and laws, and change the education systems to metric. India's conversion was quicker than that of many other countries, including its coloniser, the United Kingdom. This was helped by low popular literacy and the fact that there was previously no nationwide standard measurement system—British imperial units were used by the upper class, while various regional systems were used by the poor. The Indian model was extremely successful and served later as a model for metrication in various African and Asian countries. The National Physical Laboratory of India, located in New Delhi, is designated the maintainer of SI units in India. It also calibrates the national standards of weights and measures. History Before metrication, the government of India followed the Indian Weights and Measures Act passed in 1870 which used the British imperial system. However, many other indigenous systems were in use in other parts of the country and this was a constant problem with government officials and the public at large. P. N. Seth was the founder and secretary of the Indian Decimal Society, whose aim it was to push for the introduction of the metric system in India. P. N. Seth was assisted by others in the society, such as professors Dr H. L. Roy, Dr S. K. Mitra, and P. C. Mahalanobis, and other leading Indian scientists. Since 1930, they advocated for discarding the old chaotic system by writing in newspapers, journals, participating in debates and distributing literature. During the post-WWII interim government, there were attempts to introduce some standardisation in weights and measures but the conservative section of the