Work Step by Step
400 mm to cm From mm to cm is one place to the left. The decimal point in 400 starts at the far right side because 400 is a whole number. Then move it one place to the left. Move decimal point one place to the left. 4 0 0. = 40.0 cm 400 mm = 40.0 cm, and 40.0 cm is equivalent to 40 cm.