mm → ft
Ancient Egyptians used cubits (forearm length) around 3000 BCE, making it one of the earliest standardized units. The cubit was even used to build the pyramids!
In 1960, the meter was redefined based on wavelengths of krypton-86 radiation. Today it's defined by the speed of light traveling in 1/299,792,458 of a second.
A 4,500-year-old copper alloy rod found in Mesopotamia is believed to be one of the earliest measuring tools, marked with cubit divisions.
GPS satellites use precise length measurements accurate to within centimeters to guide billions of devices worldwide.
Why did the ruler go to school? To become a little more measured in its responses! 📏