12 inch equals 40 cm, and three feet equals 1 m, so twelve inches equals twelve divided by ten and then divided by three equals 0.4 m, and centimeters and meters are in the decimal system, so 12 inch is 40 cm when converted into centimeters. Inch is a common Chinese word? This word first appeared in the Warring States Period? . The inch of ancient Chinese characters consists of two parts: the "you" representing the hand and the "one" indicating the thing. The original meaning refers to an inch-long part from the palm to the wrist.

"Inch" is a traditional unit of length in China, and it is decimal with "ruler" and "foot". In building materials, pipes are called in inches, which is 2.54cm, instead of city inches. In liquid crystal displays, the specifications are generally 17 inch, 19 inch and 22 inch. In addition, Hong Kong people generally use "inch". For example, a 12-inch computer usually means that the diagonal is 12 inches long.

The difference between inches and inches:

1 inch =? 2.54? Cm, 1 inch? =? 3.33333333? Cm, 1 inch? =? 0.762? Inch, 1 inch = 1.3 12 inch. Inch and inch are used in different situations. Inch, as a unit of length, is mostly circulated in China, and it is also commonly used when measuring clothes. Inch is imported from abroad and is mostly used to measure the size of LCD.

In a tablet computer, the screen size is generally 7.9 inches, 9.7 inches, 12.9 inches. The size of the display screen is usually measured by the diagonal length, in inches. Inch is generally referred to as "inch" here.