Since there are 1000mL/L, and we have 400 L, there are clearly more millileters than liters (Think of the sentence King Henry Dances Many dances come monday or KHDMdcm). The L (aka M or the base value) is to the left of the m (standing for mL), so to get from M or L to m we move the decimal point 4 places to the right to get from 400.0000 to 4,000,000
