1km = 10hm = 100dm = 1,000m = 10,000cm
Although hectometer and decameter aren't used often, the way the metric system steps up/down in magnitude is a whole lot easier to remember than....
1mile = 1760 yards = 5,280 feet = 63,360 inch
And then...
1 yard is 3 feet.
1 feet is 12 inches.
Therefore 1 yard is 36 inches.
And if that wasn't bad enough, its different on water!
1 mile on land = 0.289 leagues.
1 nautical mile is not 1760 yards.... NO, if you are rowing a boat on the river, its 2,025 yards!
The BEST thing ever however is how NASA lost a many-million costing Mars Orbiter probe because someone used English measurements in 1 of the several thousands of calculations used to bring the Orbiter in orbit of Mars, causing it to crash on the surface instead. Ooops.
The English measurement system needs to go.......