One billion, represented as 1,000,000,000, consists of one 1 and nine 0’s. It is regarded as 1 x 10 to the ninth power in scientific notation, where 9 indicates the number of zeros. It is equivalent to a thousand million: 1,000 x 1,000,000.
A billion used to have 12 zeros in British English because it was defined as a million million: 1,000,000 x 1,000,000. British English has adopted the American figure of 1,000,000,000 to denote a billion, according to Oxford Dictionaries.
The nine zeros in a billion correspond to 9 place values: 0 ones, 0 tens, 0 hundreds, 0 thousands, 0 ten thousands, 0 hundred thousands, 0 millions, 0 ten millions and 0 hundred millions.