You write it: 150 000 000.
One hundred and fifty million years.
150 Million is 150 x 106 or 150,000,000
It is: 1.5*1020
It would have been 149,997,988 years BC (in 2013). But, assuming that 150 million is, at best, accurate to the nearest million years, for all intents and prposes, the answer should be 150 million years BC.
Allosaurus fossils date to between 155 and 150 million years ago. Presumably they died out around 150 million years ago.
150,000,000 150 million
150,000,000 Euros
The youngest known fossils of Apatosaurus date to 150 million years ago. Thus, Apatosaurus probably died out around 150 million years ago.
To write 150 million in standard notation, you would use the numerical digits for the number and place commas to separate the digits into groups of three starting from the right. Therefore, 150 million would be written as 150,000,000 in standard notation.
About 17,123 years.
A better question could be 'how do write write' but I think the answer you're looking for is '150,000,000'
150 millions years ago Earth was in the late Jurassic period.