Convert cm to km

センチメートル

定義
A centimeter (symbol: cm) is an SI unit of length equal to one-hundredth of a meter (0.01 m). It provides a handy subdivision of the meter for measuring small distances.

起源
Formed from the Latin prefix センチ (“hundred”) plus “meter,” the centimeter is part of the metric system’s base-10 architecture. While the meter’s realization has evolved—from Earth-based definitions to a light-speed standard—the fixed relationship (1 cm = 0.01 m) remains unchanged.

Usage
Centimeters are used everywhere the meter is too large: on school rulers, medical height charts, product dimensions, and any context requiring finer granularity—particularly in countries that have fully adopted the metric system.

キロ

定義
A kilometer (symbol: km) is an SI unit of length equal to 1 000 meters. In practical terms, one kilometer is about 0.6214 statute miles.

起源
接頭辞キロ (ギリシャ語 キリオイ, “thousand”) denotes a factor of 10³. As the metric system matured, the kilometer naturally emerged as the 1 000× multiple of the meter—which today is defined by the distance light travels in 1/299 792 458 of a second.

Usage
Kilometers are the standard for expressing land distances on road signs, maps, and in athletics across most of the world. Exceptions like the U.S. and U.K. still use miles on highways, but kilometers dominate scientific, commercial, and international contexts.