How many zeros are written in the number one million?

One million is written as a one followed by six zeros, 1,000,000, because it is a thousand thousands and each thousand contributes three. That grouping in threes is the key to the whole system of large numbers and to the way we punctuate them with commas or spaces. Every step up the ladder adds three more zeros in the modern short scale used in English: a billion has nine, a trillion twelve. There is a historical trap here. The long scale, once standard in Britain and still used in much of continental Europe, defines a billion as a million millions, with twelve zeros, and what English now calls a billion is a milliard there. Anyone reading older British sources or translated European figures needs to know which convention is in play. In scientific notation the zeros disappear entirely and a million is written as ten to the sixth power.

East Asian languages group large numbers in fours rather than threes, which is why converting figures between them takes an extra moment of arithmetic.